PRE -BUILT PORTS

NEWNES

Have YOU Joinedthe Well -paid Ranks

of the

TRAINED MEN?MANY THOUSANDS MORE ARE URGENTLY

NEEDED. PREPARE YOURSELF FOR A

BETTER POSITION AND BETTER PAY

Ambitious men everywhere have succeeded throughI.C.S. Home Study Courses. 56 also can you. Weoffer you the benefit of our 53 years' matchless ex-

perience as the creative pioneers ofpostal instruction. Since our establish-ment in 1891, more than 1,000,000British men and women have enrolledfor I. C.S. Courses.

The man with an I.C.S. Training in any one of'the subjectslisted below knows it thoroughly, completely; practically.And he knows how to apply it in his everyday work.Accountancy Draughtsmanship Motor EngineeringAdvertising Drawing Office Practice Motor MechanicAeronautical Engineering Electrical Engineering MouldingEngineer in ChargeAero- Engine Fitting Eng. Shop Practice PatternmakingAero Fitting and Rigging Fire Engineering PlasticsAeroplane Designing Fitting and Turning Quantity SurveyingAir -Conditioning Forgeman Radio EngineeringArchitecture Foundry Work Radio ServicingArchitectural Drawing Garage Management RefrigerationBoilermaking Gas -Power Engineering SalesmanshipBook-keeping Ground Engineer Sanitary EngineeringBuilding Construction Heating and Ventilation Secretarial WorkBuilding Contracting Hydraulic Engineering Sheet -Metal WorkBusiness Training Joinery Steam EngineeringBusiness Management Journalism Structural SteelworkCarpentry Machine Designing SurveyingChemical Engineering Machine -Tool Work Telegraph EngineeringCivil Engineering Marine Engineering Telephone EngineeringClerk of Works Mechanical Drawing TemplatingColliery Overman Mechanical Engineering Textile DesigningColliery Management Mine Electrician ToolmakingCommercial Art Mine Fireman WeldingConcrete Engineering Mine Surveying WoodworkingDiesel Engineering Mining Engineering Works Engineering

And most of the Technical, Professional, and Matric Exams.Special terms for members of H.M. Forces and discharged disabled members of

H.M. Armed Forces.

If you need technical training, our advice on any matter concerningyour work and your career is yours for the asking-free and withoutobligation. Let'us send you full information regarding the subject in which youare specially interested. DON'T DELAY. Make "ACTION " your watchword.

The successful man DOES to -day what the failureINTENDS doing to -morrow. Write to us TO -DAY

...Use this CouponillMEI ........ 5.1.11111Mil

INTERNATIONAL CORRESPONDENCE SCHOOLS LTD.Dept. 95, International Buildings, Kingsway London, W.C.2.

(Use penny stamp on unsealed envelope)

Please se rd me particulars of your courses in

NaMe Age

Address

THE " FLUXITE QUINS "`AT WORK

" I've fixed up your trombone,"said OH,

"With FLUXITE, T'was broken,

YknSaid EH, H. " Fixed is rightWell, no practice to -night;

You've soldered the darn toand fro

For all SOLDERING work-you need FLUXITE-the paste flux-with which even dirty metals are soldered and " tinned." Forthe jointing of lead-without solder ; and the "running" of whitemetal bearings-without " tinning " the bearing. It is suitablefor ALL METALS-excepting ALUMINIUM-and can be usedwith safety on ELECTRICAL and other sensitive apparatus.

With Fluxite joints can be " wiped " successfullythat are impossible by any other method.

Used for over 30 years in Government works and by leadingengineers and manufacturers. Of all Ironmongers-in tins,8d., 1/4d. and 2/8. Ask to see the FLUXITE SMALL -SPACESOLDERING SET-compact but substantial-complete withfull instructions, 7/6.$ TO CYCLISTS ! Your wheels will

NOT keep round and true unless thespokes are tied with fine wire at the crossingsAND SOLDERED. This makes a muchstronger yheel. It's simple-with FLUXITE

-but IMPORTANT.

THE " FLUXITE"GUN puts-" FLUX-ITE " where youwant it by a simple

pressure.Price 1/6 or filled

1/6.

ALL MECHANICS WiLL HAVE\

FLUXITEIT SIMPLIFIES ALL SOLDERING

Write for Book on the ART OF "SOFT ** SOLDERING and for Leaflets onCASE -HARDENING STEEL and TEMPERING TOOLS with FLUXITE.

Also on WIPED JOINTS:. Price Id. Each.FLUXITE LTD., Dept. P.M., Bermondsey Street, S.E.I

S. TYZACK & SON LTD.INCORPORATING GEO. ADAMS

"LONDON'S FINEST TOOL SHOPS"THE NE1V " ZYTO" PRECI-

SION HENCE! SAWWith Canting and Rise and

Fall TableRack Feed and Locking Handle.Specially designed fcr clean andaccurate cutting of mitres,angles, etc. Extra long rippingSense, with tine adjustment.Ball -bearing spindle. Cleanfinish throughout. Tablemeasures 18in. by 14in. Diameterof saw, 10in. Vertical cut. 2fin.Illustrated Leaf let and Price on

application.MOTORISED MODEL, withMotor and Bench Saw

Mounted on one-piece baseAccurately aligned, and completewith Vee belt drive and starter.Illustrated Leaf let and Price on

application.DELIVERY FROM STOCK

" ZYTO"Super Quality SlidingTallstock Dieholder.

No. 1 M.T. shank, long barrel,precision finish. For 13'161n.O.D. dies. Price 10/6. For Dn.O.D. dies, 1343. With No. 2

M.T. shank, 15/9.DELIVERY FROM STOCK

ELECTRIC GRINDERS ANDPOLISHERS(Double -ended)

1-I h.p. motorsComplete with Wheels and

Polishing SpindleFull details on request

DELIVERY' FROM STOCK

S, TYZACK & SON LTD.,341-345, OLD STREET, LONDON, E.C.1

Telephone : CLE, 4004-5-6

December, 1944 NEWNES PRACTICAL MECHANICS 73

Model enthusiasts of all ages to -day ' make do ' withtheir pre-war Bassett-Lowke models ; but we promiseyou that as soon as circumstances allow we shallput into action our plans for making even betterscale models that will delight the most exacting.Our staff in London or Manchester would welcome avisit from you and will gladly give assistance on any

model matters.Wartime Stock List (1.11.3), price 4d., post free.

" Building a 21,in.gauge Flying Scots-man," fully illustrated.

Price'.ls.

" How to Build aTraction Engine,"illustrated. Price 6d.

All the above post paid.

" Laying Model Per-manent Way," illus-trated. Price 3d.

BASSETT-LOWKE LTDNORTHAMPTON

LONDON : 112; -High Holborn. W.C.I.MANCHESTER : 28, Corporation Street, 4.

Do you take Winter Snapshots?

If so send for these booksSend us your name and address and enclose 3d. instamps for the following. A booklet entitledHome Photography. This will teach you how todevelop your own negatives, how to make printson gaslight or bromide paperand how to make enlarge-ments. Well-known expertshave written full, easy -to -

follow directions on these"subjects. Then there is a

folder giving the Time andTemperature tables for dishor tank development withAZOL and a lot of useful hintsabout the use of this famousone solution Developer. Theother booklet is a fully illustra-ted list of chemicals, sundriesand accessories which will behelpful to you in your hobby.

FOR 3d. IN STAMPS WEWILL SEND YOU THESETHREE PUBLICATIONS

SPECIALTRIAL OFFER

For 2/3 P.O. Johnsonswill send you post free(G.B. only) a trial setof Chemicals, including1 -oz. bottle of AZOL,to' develop eight spools21 in. by 3.1 in. 4 -oz,tin ACID -FIXING making30-60 oz. solution, onepacket AMIDOL DEVELO-PER, enough for 2 to 3doz. bromide or gaslight

prints.

See your local dealerfor any further supplies

To save time, be sure you mark your envelopeDepartment 41.

JOHNSON & SONS Manufacturing Chemists LTD.,HENDON, LONDON, N.W.4 Established 1743

1

Pyrumafor Paid ModellyYou just mould this plastic cement to any shape.

It sets to stone hardness by air -drying or baking.Paints or colours are then added.

The realistic village setting as photographed wasmodelled throughout in Pyruma. Sections werejointed with Tiluma, the finely adhesive jointingcement. Contour maps, figures, miniatures,plaques, etc.-all can be modelled just as easilywith these plastic cements.

Sankey's Pyruma and Tiluma are obtainable intins from Ironmongers, Hardwaremen, Artists' andHandicraft Shops. Send id. stamp for IllustratedInstructions for Modelling leaflet to J. H. Sankey &Son, Ltd., Modelling Dept. 5, Ilford, Essex. Co

PLASTIC CEMENT

74 NEWNES PRACTICAL MECHANICS December, 1944

CHEMISTRYARE YOU INTERESTED?Whether you dabble in experiments orpursue a course of serious study, you will

rneed our LABORATORY EQUIPMENT. Westock a wide range of APPARATUSand CHEMICALS atreasonableprices.

E)(PERWE' S °t4tSEND Stamped

Id. addressed envelope forFREE PRICE LIST.

SPECIAL OFFERS(Carriage Paid)

10/6A Useful Selection of

SCIENTIFICAPPARATUS

for Students

2,1/-A Goad Assortment of

APPARATUStogether with

CHEMICALSBooklet of Experiments with each Offer

BECK (Scientific Dept. A), 60, High Street, StokeNewington, London, N.I6.

Slide rulefor 516d

HARDTMUTH'S meet a popular need of the momentwith the ' Classic' Slide Rule. Four scales-adequatefor all ordinary calculations. Inch and centimetre scaleson edges. Completely accurate, and strongly made ofseasoned Honduras mahogany, tongued and groovedand reinforced with flexible stock unaffected byclimatic change. The strong, view -free, unbreakablecursor has metal ends.

Classic Slide Rule, in strong pull -off shoulder boxwith full instructions : Series I, 5" Pocket Model,price 516. Series I, 10" Model, price 716. From allstationers and drawing material dealers, but ifany difficulty in obtaining write direct.

OTHER ' CLASSIC ' SUCCESSES.T -Squares, 24" seasoned Honduras Mahogany

bevelled, price 61-.

Set Squares (of stout celluloid):6", 45', price 114 each ; A", 60°, price 114 each ;8", 45', price 212 each; 10", 60°, price 212 each.

(Other sizes supplied to order.)

orzi alfrr,en' Pia. Anti

<1:011-1-NOOR" and " MEPHISTO"-perhaps the two best-known pencils inthe world-will be in plenty again.

L. & C. HARDTMUTH 0.7.1Ti)LTD.

Temporary address : 44, Alexandra Road, Epsom, Surrey.

C

0

9

a

(-3

Snot, As", ',FS. Zoo.. **troll En.

Keep Your' 1 4$ Se teamand Hands Well Groomed!

'Perox-Chlor is the Magic Nail Cleaner and HandBeautifier It takes out the dirt, makes the tips IvoryWhite and leaves the hands SOFT. WHITE ANDFRAGRANT.

Your nails and hands will always look well groomedwhenusing this NEW SCIENTIFIC TREATMENT.NO MESS !! NO BOTHER ! I just squeezelittle on your nail brush and shampoo your nails andhands. Presto Your nails and hands becomeimmaculate in:lei:Ns:sly.

Thousands use Perox-Ghlor every day, And whet aboon i t 13 to surgeons, doctors. gardeners, motorists,housewives, typists, nurses. sailors, soldiers, firemen,farmers and many more besides.

I/9i, 4/4, in tubes and feel. From all chemistsand stores. A I/9) tube or jar lasts for months.

OUR HONEST GUARANTEE. Order a I/9)tube or jar from your chemist to-clav, Use it fora few weeks. If you are not absolutely amazed atthe wonderful improvement to your nails and hands,post us the wrapper and we will refund your moneywithout question or quibble. Do it now!

Fair supplies are still available.

Perox- ChlorCA.4,tA4t

rt Nt S 141800,004 S ,1131r0, NEWCAST1.303orret,

OaOrisne Icons m,ntf /13/wELL to/ tm.ya"

YOU CAN TIN ANY

HOYT'SMETAL QUICKLY AND EASILY

with

TINNING COMPOUNDconsisting of powdered metal combined with an active flux!ic SEPARATE APPLICATION OF FLUX, SOLDER OR TIN REQUIRED

JUST CLEAN THE JOB AND FOLLOW DIRECTIONS

Heat the work and just sprinkle the powder evenlyupon surface to be tinned. The flux should " boil "and its cleansing action will be assisted if the surfaceis scrubbed with a wire brush at this stage. Whenflux has all melted and the surface is tinned evenlyall over, remove from'heat and wipe with a clean rag.

Price 6/3 per lb. nett carr. paid.HOYT METAL CO. of GT. BRITAIN, Dept. PM. DEODAR RD., PUTNEY.

LONDON, S.W.15

BERRY'S(SHORT WAVE) LTD.

In addition to the usual radio parts, we carry a mostcomplete range of

RADIO AND ELECTRONIC EQUIPMENTincluding C.R. Tubes 2iin., £3 6 0 ; 4fin., £6 1 0. Meters 0-5 ma., 57,6 :C-1, 75/8. Meico 5w. Amplifier, £16 10 0. Rothermel Crystal Mikehead£4 15 0. Pick-ups, 73/6, 78/9. Ceramic S.W. Variables .0001. 4.6 : .00016,.,4 9 ; 15 mmf., 318 : 25 mmf., 3/9 ; 40 mmf.. 4/6 : 75 mmf. midget.Precision 4in. S.M. Dial, 91, with driving head and vernier, 35!-.S.M. Drive,.

1. with station named dial escutcheon and glass. 8/6. " P " Coils. 2,3,2 6. I.F.s, 716. Metal Cabinets with hinged lid, panel and chassis. 39/6,63.-. Jacks and Plugs, 2:6 each. S.W. II.F. Choices, 2/13. All Wave 2.5 ma.:3-.6. Toggle and Rotary switches. Ceramic Valvebases. Stand-offs, feedthroughs. Formers, Radio Manuals. Send Id. stamp for full list " P.M."

to :-,

25, HIGH HOLBORN, LONDON,(Telephone : Holborn 6231.)

December, 1944 NEWNES PRACTICAL MECHANICS 75

Az

This,is the latest MYFORD Type " M "3r Lathe, of the type previouslymanufactured by Messrs. DrummondBros. Ltd. The machine illustrated is

mounted on a Myford-designed motorisedstand, with vee-rope drive throughout.This is an example of the manner inwhich Myford are enhancing the prestigeof a machine already famous all overthe World.

Replacement parts and accessories for Lathes require noMachine Tool Control permit. Apply to your Tool Dealeror to Myford Engineering Co. Ltd. Permits are required

for the purchase of complete Lathes and Motors.

Full particulars on application

MYFORD ENGINEERING CO. LTD.BEESTON : NOTTINGHAM

Telephone : Beeston 54222 3 '4

75.73

ROTARYQUICK MAKE & BREAK

BRITISH MADE THROUGHOUT

For all purposes - fully tested Switches tocustomers' requirements.

Let us use our long experience tosolve your Switching problems.

TOK SWITCHES LTD.,CAMBRIDGE ROW, BU R RAGE ROAD,

WOOLWICH, S.E.18

ENGINEERS, DRAUGHTSMEN ANDMATHEMATICIANS NEED

THE

@11FRACTORROTARY CONVERSION TABLE

The most compact, handy andaccurate table ever devised. . . .

Converting inches to millimeters-millimeters to inches-to an accuracyof 7 decimal places is a matter ofseconds with the new "Con.tractor." The readings, rangingfrom " general pui pose " to " extraaccurate." are clear and foolproof-the table washable and virtuallyindestructible. For fulter'cletalls write

to W . J. Steele & Co., Ltd., 641, Staines Rd., Bedfont, Mdx.

OBTAINABLE FROM ALL W. H. SMITH & SON'S

.

S to INCA.

SHOPS

Spotting the movements of enemy ships. Mapping the invasionbeaches. Plotting German gun sites and countering the flyingbomb. These are just a few of the grand jobs done by Ilford Film.When peace comes, Ilford photographic materials, better thanever before, will come back into general use.

ILFORD makers ofLIMITED

films

76 NEWNES PRACTICAL MECHANICS December, 1944

PREPARE FOR PEACE -TIME COMPETITIONIn the more competitive days of peace, technical training will be a vital necessity to theEngineer who wishes to safeguard his position and make advancement. " ENGINEERINGOPPORTUNITIES " will show you how to secure this all-important technical trainingquickly and easily in your spare time. This 100 -page book is full of valuable informationand explains the simplest way of preparing for recognised Examinations. Among thecourses described are

MECHANICAL ENGINEERING GROUP ELECTRICAL ENGINEERING GROUPA.M.I.Mech.E.City & Guilds

EstimatingForemanship

A.M.I.E.E.City & Guilds

Electricity SupplyElectrical MetersGeneral Mechanical Eng. Jig & Tool Design General Electrical Eng. Electrical DesignDiesel Engines Viewing & Inspection Alternating Currents IlluminationDraughtsmanship & Tracing Welding Power House Design InstallationsWorks Management

Press Tool WorkSheet Metal WorkMaintenance Eng.

Tractionflains Eng.

TelegraphyTelephonyPattern Making Metallurgy

Foundry Practice Refrigeration WIRELESS GROUP

COMMERCIAL ENGINEERING GROUPA.M.I.P.E. Cost AccountsCommercial Eng. Languages

CIVIL ENGINEERING GROUPA.M.I.C.E. Road Eng.Inst. Mun. & Cy. Engineer HydraulicsA.M.I.Struct.E. Municipal Eng.M.R.San.l. General Civil Eng.Sanitary Inspector Structural Eng.Specifications Reinforced ConcreteStructural Design Railway Eng.

SURVEYING AND BUILDING GROUPA.R.I.B.A.F.S.I.A.M.I.H. & V.F.L.I.O.B.F.A.I.

Costing & ValuationsHeating & VentilatingClerk of WorksSurveying & LevellingBuilding (all branches)

A.M.Brit.I.R.E. Advanced WirelessCity & Guilds Radio ServicingGeneral Wireless TelevisionShort -Wave Wireless Talking -Picture Eng.

AUTOMOBILE ENGINEERING GROUPA.M.I.A.E.M.I.M.T.City & GuildsI.A.E. Repair Certificate

General Automobile Eng.Garage ManagementElectrical EquipmentHigh Speed Diesels

AERONAUTICAL ENGINEERING GROUPA.F.R.Ae.S.R.A.F. (Maths.)Pilots' LicencesGround Licence

Aero EnginesNavigators' LicenceAeroplane DesignMeteorology

UNIVERSITY DEGREESLondon Matriculation University EntranceSchool Certificate Intermediate B.Sc.

WE DEFINITELY GUARANTEE

"NO PASS NO FEE"ii you are earning less than £10 a week you cannot afford to miss reading " ENGINEERINGOPPORTUNITIES " ; it tells you everything you want to know to make your peace -time future secure,and describes many chances you are now missing. In your own interest we advise you to write for yourcopy of this enlightening guide to well -paid posts NOW-FREE and without obligation

BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY410A, SHAKESPEARE HOUSE, 17, STRATFORD PLACE, LONDON, WI

THE B.I.E.T. IS THE LEADING INSTITUTE OF ITS KIND IN THE WORLD

December, 1944 NEWNES PRACTICAL MECHANICS 77

InlandAbroadCanada

SUBSCRIPTION RATES(including postage)

- - - 10s. 6d. per annum.- 10s. per annum.

- - - 10s. per annum.Editorial and Advertisement Office : " Practical

Mechanics," George Newnes, Ltd.Tower House, Southampton Street, Strand, W.C.2

'Phone : Temple Bar 4363Telegrams : Newnes, Rand, London.

Registered at the G.P.O. for transmission byCanadian Magazine Post.

Copyright in all drawings, photographs and articlespublished in " Practical Mechanics " is speciallyreserved throughout the countries signatory to theBerne Convention and the U.S.A. Reproductionsor imitations of any of these are therefore

expressly forbidden.

PRACTICALMECHANICS

Owing to the paper shortage " The Cyclist," "Practical Motorist," and "Home Movies" aretemporarily incorporated.

Editor : F. J. CAMM

VOL. XII DECEMBER, 1944 No. 135

FAIR COMMENT BY THE EDITOR

The Gas IndustryALTHOUGH the gas industry is being

superseded for certain purposes byelectricity and the development of the

Grid Scheme, it is still a most important branchof commerce. There are many who believethat we should develop a gas grid on the linesof that developed for electricity. There areothers who think that all power, whetherelectricity or gas, should be developed at thepit head. As it is, coal is mined, ca -tried by railto remote parts of the country, and thendeveloped into power. This is wasteful oftime and makes the product costly.

We are told that after the war we shall not be free to choose in the new houses betweenelectricity and gas. We shall be told to use

happens to suitlocal conditions.

Technical ProgressIn its 15o years of existence, the gas

industry has made ,many notable advances inthe production and utilisation of gas. Progresshas never been more rapid than it has beenduring the past 4o years. These advanceswere the subject of the presidential addressto the Institute of Fuel delivered by Dr.E. W. Smith.

Dr. Smith had no doubts about the futureposition of. the gas industry. Remarking thatit has become the fashion in some quartersto assume that the gas industry is *rapidlycoming to the end of its useful life, and toassume that for many years there have beenlittle or no .technical developments in coalcarbonisation, he said : " I believe theopposite to be the case. Not only is gas beingused more and more as a heating medium,but the possibilities in the future for thedevelopment of the carbonising industries aregreater than they have ever been."

Advances are due to the united effort of allengaged in the gas industry-those who makeand distribute and sell gas from the gasworks,those who design, build, or manufacture -plantin which gas is made or used, and the researchmen either in individual firms or undertakingsor working under the co-operative scheme ofresearch initially set up by the Institution ofGas Engineers and now under the GasResearch Board. The period of 4o yearscovered in the presidential address was a timeof flux, for new and revolutionary systems ofgas manufacture were in process of develop-ment.

In 1907 the Institution of Gas Engineers'Research Fellowship was instituted at thethen recently established Fuel and MetallurgyDepartment of the Leeds University. In thesame year the first Joint Committee of theInstitution of Gas Engineers and LeedsUniversity-the Heating by Gas Committee-

was established. Thus began a long associa-tion between these two bodies, which wascrowned in 1910 by the endowment of theLivesey Professorship in the reconstitutedDepartment of Coal, Gas and Fuel Industriesat the university with the late W. A. Bone asthe first professor. One of the most importantresults of the work of the Joint ResearchCommittee at Leeds was to attract into theindustry men of high scientific ability who,after a period spent upon research, usuallysettled down in some gas undertaking orcontracting firm.

Improved Refractory MaterialsParallel with these advances in education

and research came an effort to improve thequality of refractory materials used in gasretorts. The result was that whereas in 1910the average life of horizontal retorts was foundto be 797 days and, with patching, 1,257 days,in 1934 the average life was found to haverisen to 1,70o days and it was a fairly commonexperience for them to attain a life in excessof 2,000 days. The latter figures were obtainedwith much higher combustion chambertemperatures than' appertained in 191o, andbetween the dates of the questionnaires theaverage make of gas per ton of coal carbonisedhad been increased by over 4o per cent. Ahandsome reward was thus being rdaped forthe time and money spent .

The first three years of the century hadseen the introduction of two new systems ofcarbonisation, intermittent vertical retorts inGermany, and continuous vertical retorts inthis country. The work of the Heating byGas Committee set up in conjunction withLeeds University in 1907 led to the publicationfor the first time of accurate data upon thedistribution of the heat supplied to the fire.It is not too much to claim that the informationthus obtained provided the initial impulse tomanufacturers to improve the design of gasfires which has raised the average radiationefficiency from 28 per cent. in 1909 to over5o per cent.

Immediately after the last war the experiencethus gained made it possible for the gasindustry to seek the necessary power fromParliament to adopt a calorific value standardin place of illuminating power. This resultedin the Gas Regulation Act of 1920, which setup the requisite standards with appropriatesafeguards for the consumers. This was,indeed, a " Magna Charta " for the industry,and its influence on subsequent developmentshas been profound. One of the most interest-ing differences between now and the earlierpart of the century is that whereas formerlyall the water -gas was made in separate water -gas plants, to -day a considerable proportion

of water -gas is produced during carbonisationby steaming intermittent and continuousvertical retorts.

Research WorkLaboratory investigations have enabled the

behaviour of coals in the retort to be forecast.Since no two coals have exactly the samecharacteristics, this has been a most importantstep. The laboratory control has been furtherextended to ma t e r i a l s of construction.Refractory material is a field in which agreat deal has been done with the ableassistance of the Refractory Materials JointCommittee of the Institute of Gas Engineers.Experience has shown -that careful laboratorycontrol of refractory materials and jointingcements used in construction is essential, and,moreover, acts as a stimulus to manufacturersto maintain their quality, whilst at the sametime encouraging the development of improve-ments. Cast iron also plays a most importantpart in the carbonising industries, and thework of the British Cast Iron ResearchAssociation in improving the mechanical andchemical properties of cast iron have beeninvaluable.

A very important method of developmentwas that of incorporating advances made ingas practice all over the world.

In coke production, in benzole recovery,in removal of naphthalene and water vapourfrom the gas to prevent blockage of mains,and in the use of coke oven gas to the advan-tage of industry and the domestic consumeralike, the gas industry has done a great dealof good work within the period under review.

Flying Model Aircraft-Law RelaxedIN view of the changed war situation, the

restrictions governing the flying of modelaircraft have now been relaxed to someextent. Subject to the following conditionswhich supersede those previously published,any type of model aircraft (including gliders)no matter what the motive power, may nowbe built and flown anywhere in the BritishIsles. Here are the conditions : Modelsmay not be flown between the hours of sunsetand sunrise.

Models may not be flown in officiallyprohibited areas, or within two miles of anyR.A.F. station.

All petrol model aircraft must be set tofly in a closed circuit only.

Wing span must not exceed soft.Maximum engine running time for petrol -

driven model is to be 45 sec.Maximum airborne time of any petrol -

driven model aircraft must not exceed2 min. for any single flight.

78 NEWNES PRACTICAL MECHANICS December, 1944

The Great Pre -built Structures which Forrried the Port Erected by British Engineers on the Beaches

of Normandy at Arromanches

section of the Royal Navy had to predict tothe nearest foot the mean height in any windof the breakers along any stretch of theNormandy coast.

A line of steel columns filled with con-crete form a - breakwater, and pontoonbridges, made of barges arranged cross -wise,carry the roads to the pierheads where theships unload their varied cargoes. Upwardsof 20,00o men worked on the breakwatercolumns alone, in England, before they weretowed to their dispersal points on the coast,and altogether about 600,000 tons of concreteand 75,000 tons of steel were used.

Floating PiersThe floating piers, which are clearly shown

in some of the accompanying illustrations,were the designers' solution to the problem oflinking up the artificial wharves, far out to,sea, with the beach. Anti-aircraft guns on'platforms on the caissons guard the harbour.Some of the units had to be towed from asfar away as Leith, in Scotland.

The "Mulberry" Invasion Harbour

A concrete caisson under construction, to be used as a breakwater. The huge dimensions ofthis structure will be evident on comparison with the figures of the men seen on the right-hand

end of caisson platform.

WITHIN 12 months rif the testswith models Britain built two ports,each as large as Gibraltar, and after

being towed across the Channel the pre-built units were erected off the coast ofNormandy to form a harbour which wasin working order a week after D-day. Withits help we landed a huge army, thousandsof lorries and other vehicles, and thousandsof tons of equipment and supplies, despitethe worst June for 4o years.

The transportation of the blockships, thegigantic caissons, and other equipmentinvolved the towing of the units from theirconstruction sites to the assembly parks offthe South Coast, amounting to over 500tows.

Before the vast plans could be put intooperation experts of the meteorological

Large concrete caissons forming a main deep -water breakwater. Note the anti-aircraft gunsfor guarding the harbour.

A spud pierhead off Arromanches after a cross -channel tow.

The caissons, which contained crews'quarters for use during the passage, weretowed across Channel by one large sea -goingtug of about 1,500 h.p. On arrival off theNormandy beach they were manoeuvred intoposition with the help of smaller tugs.Special valves were then opened, allowingwater to fill the caisson and sink it in place.The valves were left open so that the waterlevel remained the same inside and out. Ittook about -twenty-two minutes to sink thelargest -size caisson.

The illustrations give a good idea .of theimmensity of the work which was the largestand most rapidly erected military under-taking in history.

December, 1944 NEWNES PRACTICAL MECHANICS 79

P re -built Ports

A hospital ship clearing casualties from the endof a floating pier, so constructed as to rise and fall

with a loft, tide.

A wharf formed of seven pierheads in line.

A pier, laden with traffic, and giving exit toArromanches.

Two pre -built ports, each as big as Gibraltar,were manufactured in Britain in sections, towedacross the channel, and set down on the coast ofNormandy, at Arromanches. The use of the pre-fabricated port greatly simplified the problem ofsupplying the Allied Armies in France. A comparisonbetween the sizes of the ships and vehicles, and thevarious units which make up the port, illustrates the

immense nature of the undertaking.

Inshore end of a pier being placed into positionon the beach at Arromanches.

Concrete caissons in position forming a shallowbreakwater.

Another view of one of the piers showing a tankmoving towards the beach.

80 NEWNES PRACTICAL MECHANICS December, 1944

The Aircraft Rocket -projectileIT was disclosed recently that four types

of British aircraft, the Typhoon Beau -fighter, Hurricane, and Swordfish, have

been modified to carry rocket -projectiles.Each aircraft is fitted with eight launchingrails, four beneath each wing, from which thesame number of rocket -projectiles are fired,' either in pairs or as a complete salvo of eight.The launching aircraft experiences no recoil.

The projectile itself consists of a heavygauge steel case, containing a cordite pro-pellant charge, with a shell -shaped explosivehead. The propellant charge is electricallyfired.

It will be remembered that the aircraftrocket -projectile was first made known sometwo years ago, the Russian Stormovik IL2being the first machine to be so equipped.Later, the two -seat Stormovik IL3 and theLagg 3, Mig-3 and Yak -r single -seatfighters. were similarly fitted. The Germantank formations have been their chief prey.

The Anti -bomber Rocket -projectileThe Germans, too, have not been slow in

adopting the aircraft rocket projectile, andduring the latter months of last year aFocke-Wulf rgo fighter development, intendedfor the purpose of disrupting Allied bomberformations, made its appearance, along withother converted types, the Ju. 88, the Me. ragand Me. r to.

Two " projector tubes " only are fittedbeneath the wings of the single engine fightersand these carry the 2.5in. rocket shells.Four to six wing launching attachments arefitted to the twin engine aircraft and fromthese are fired the larger 6in. and 8in. shells.Reports have indicated that some bi-motoraircraft have the " projectors " mountedbeneath the fuselage, instead of under thewings.

The projectiles are axially spun for stability,rotation being effected by offsetting theexhaust nozzles which are spaced around aconical cbllar at the rear of the rocket. Thelarger projectile is a development of theGerman 21 cm. cannon shell, a rocket unitbeing added behind the explosive charge.The maximum range of this projectile, whichweighs 200 lb., is in the region of 6,500yards. A " stick " formed substance, similarin character to cordite, is used as propellant.

Its Use in Modern Warfare

The long-range Lockheed Lightning P38 fighter 'plane. This all -duty aircraft has been used fora variety of purposes. Its climb, speed and fire power give it an advantage over enemy fighter'planes. Owing to its increased range, the Lightning can escort bombers all the way to Berlin.

The firing period, at maximum, is twoseconds.

The range of these rockets is such toenable the " projector " aircraft to remainout of range of the bomber's defensivearmament while delivering an attack.

American Rocket -carrying 'PlanesMore recently, reports from the Far

Eastern war theatre have given the names ofseveral American aircraft, both land -basedand sea -borne, now fitted for R.P. (the Ser-vice abbreviation for " rocket -projectile "),amongst which are included such notabletypes as the Thunderbolt, Lightning, Mus-tang, Tomahawk, Airocobra and Dauntless.According to correspondents, these aircrafthave achieved considerable success in.attackson Japanese shipping and troop concentra-tions.

A striking contrast. A rocket -carrying Typhoon on a temporary airfield is passed by the farmcart of a Normandy farmer who is getting on with his work.

Increased Impact VelocityA prominent advantage of the rocket -

projectile over the conventional lightbomb for terrain and marine attack is theincrease in impact velocity. Whereas anormal type bomb released in the course ofa ground strafing assault, for instance, willreach the objective at approximately the samespeed as the attacking aircraft, the rocket -projectile, due to its inherent power, willarrive at the target at a considerably improvedvelocity. The higher the speed of release,the greater is the velocity of impact. Therocket -projectile is, in consequence, able toobtain a greater penetration than the conven-tional light bomb, and reports from theRussian front suggest that, under certain con-ditions, the light rocket -projectile is able tocause destruction comparable to that of theheavy bomb released from a high level.Improved Sighting

Another point of significance is the reducedliability to error with regard to sighting,which is effected by pointing the aircraft atthe target, probably with the aid of a normaltype gun -sight. The combined action ofgravity and forward motion result in thenormal type bomb falling with a curvedtrajectory. The rocket -projectile, on theother hand, due to its independent propul-sion, is able to maintain a highly accurateflight path, coinciding very nearly with theline of sight.

The greater precision and improved pene-trating potential of the rocket missile wouldespecially suggest advantage in attacks onheavily armoured ships, tanks, and concreteemplacements. Due to the total absence ofrecoil, the sole limiting factor to projectilesize is the aircraft carrying load, and inconsequence it is not unreasonable to assumethat rocket -projectiles bearing explosivecharges rated in several hundreds, perhapsthousands, of pounds will later be employed.When that time comes, it should be possibleto end the career of the most heavilyarmoured war -vessel afloat with but a singlehit.

December, 19 44 NEWNES PRACTICAL MECHANICS 81

THE mechanical rectifier has beenpractically superseded by a four -valve

,P circuit consisting of hot cathodevalve -tubes, working on the same principleas the hot cathode X-ray tube. In somecircumstances one or two valves areflied and in the case of a three-phase alter-nating current, a six -valve circuit is used.1'o demonstrate what is required, a diagramof the mechanical rectifier is perhaps easierfor the reader to understand (see Fig.The rectifier consists of a circular disc ofinsulating material, such as bakelite, fixedon the shaft of a motor which runs synchron-ously with the alternating current. Fourfixed metal contacts are attached and areconnected by a wire in pairs. As the discrotates the metal contacts pick up the currentand distribute it so that the current travelsin one direction through the tube. It wasa noisy instrument because of the runningmotor, and also because of the sparkingwhich took place at the contacts. The valvetubes are noiseless. Since the introductionof the transformer, we have many advantages ;one is that we can control the output in thesecondary circuit at a uniform voltage ; thisis done by a piece of apparatus known as theauto -transformer ; it is situated between themain supply of the primary windings off' thetransformer. It is just another form of closedcore transformer ; its primary windings

ProAress in XraysThe Advances Malt in Apparatus and the Application of X-rays

By A. J. WALTON, F.S.R.(Concluded from page 44, November issue.)

exposure time is completed, breaks theelectric circuit automatically. This ensurescorrect time of exposure, which is an importantfactor. Dark room equipment has improvedconsiderably. From developing dishes totanks which take the films in the upright

0

pug;MMUS

H7: Transformer

AutorransfortnerCoorrol.

Fig. iz.-Circuit diagram of transformer andauto -transformer control.

Fig. 4.-" Aerial " tubular fittings for carryingthe connecting cables for X-ray apparatus.

consist of a fixed number of turns and thesecondary is tapped at a number of points(see Fig. 2).

The tapped wires are connected to crankstuds on the top of the control table byusing one or other of which we can varythe ratio of windings and therefore thevoltage we apply to the high-tension trans-former. Another advantage is the " pre -reading kilovoltmeter." Space dots notpermit an explanation of the instrument.Briefly, we have a voltmeter on the controltable which measures the primary voltage,but it is calibrated in kilovolts and shows thetension available in the secondary circuit.The importance of this is that we can pre-setthe required kilovolts to be applied to theX-ray tube, which varies considerably withthe variety of work and even with differentpatients. Another advantage is the electricallycontrolled timer which when the required

position in filmhangers (see Fig.13). The films areprocessed in chemi-cal solutions keptat a constant tem-perature by thermo-static control. Fromweighing drugs tohaving them alreadyweighed in packets.A much improvedsafe lighting system.From glass platesto . double -coatedfilms, perhaps thebiggest photo-graphic advance ofall ; electric heaterfor drying the films,etc. Regarding thedangers in X-ray

departments. In the early days, the tubeand coil were connected with ordinaryelectric wire. Apart from the electricaldangers, there was a lot of static dischargethrough sparking and bristling from thewires ; the air became ionized ; this

Fig. 13.-A developing hanger for X-ray films.

caused a very serious blood conditionwhich actually caused death. The patientswere not in it long enough to be troubled ;it was the X-ray worker who suffered. Thissystem of wiring was replaced by tubingthrough which necessary connections werecarried (see Fig. 14). This, together with aproper system of ventilation, did away withmost of the trouble. Since the introductionof the shock -proof tube, with its thick coveredcables and perfect connections, one can sayit has been overcome. The dark developingroom troubles have been cured by properventilation, large and brighter rooms andfewer hours of work. The X-ray workers as awhole are now protected by definite hours ofwork and holidays which, it is recommended,should be spent in the open air as much aspossible.Army Apparatus

During the South African War, the Armyused in South Africa a loin. induction coil(a coil which sparked min. in air), a hammer

Fig. 15.-A portable X-ray unit of the last war.

82 NEWNES PRACTICAL MECHANICS December, 1944

Fig. i6.-Adjustable X-ray apparatus usedin conjunction with an operating table.

interrupter, 2 -volt accturfulators and a smallgas tube. The writer had the opportunity ofseeing many X-ray results which were takenin Africa ; in the main they were goodpictures. Of course, they were all taken forgunshot fractures of bone or for foreignbody (bullet and bits of shrapnel). Therewas no call for the large and intricate examina-tions which are demanded to -day. The

A.-Mirror.B.-Centre of

mirror.C and D.-Mir-

ror support.E.-Iris dia-

phragm.H. - Sighting

tube.J. Dead -centre

hinges.K - Telescopic

pointer.L-U-shaped

support.

Fig. 18 (above).- Appar-atus used for the localisation

of a foreign body.

19 (right). - AnX-ray photograph of a

kidney interior.

writer, at a laterdate, took manypictures under thesame conditions ;on one occasipnbeing requestecrtotake the picturesof the kidneys of avery1 corpulentBishop of London ;there was no meansof cutting outscatter or secondaryradiations, eachexposure was tominutes ; to -day thesame exposureswould be three orfour seconds. InIndia pack muleshave carried thesame kind of appar-atus over the hillsto X-ray cases.When the last warcommenced, t h eArmy Field Serviceoutfit was a izin.coil, a mercury inter -

in the South African War. Army apparatus,generally, has to be portable. As hospitalswere established and electric mains wereavailable, much larger types and apparatusof all kinds were soon installed. Portable units.chiefly for casualty clearing stations, werearranged complete on wagons (see Fig. t5).A 3 -ton lorry with a 3 kW dynamo, havingan output of 15o volts, 20 amperes, drivenfrom the main gear box. The developingroom was in the lorry with a plentiful supplyof water ; the body of the lorry could be usedas an examination room, or a tent could beextended for the purpose. The injuries ofthe war taxed the brains of many surgeons ;special beds of all kinds were designed, somebeing particularly wide for the full extensionof both legs. The surgeon, after setting thefracture, would not wish to move the patientfor the removal of a piece of metal whichbegan to give trouble. The writer was re-quested amongst many other such requeststo design a piece of apparatus which wouldovercome these difficulties. The result of hiseffort is shown in Fig. 16. To -day, thesame movement is used for quite a differentpurpose.

In this war the transformers with thehot cathode tubes are in use. The' original

Fig. 17.-An improved field service X-ray unit.

rupter, 36 volts accumulators, a small petrolengine for charging, a couch and a gas tube ofa larger size and improved make to that used

field service sets wue made up with a smallportable transformer. One unit is of par-ticular interest because it represents anothergreat advance : it is portable yet has sufficientoutput for work in a hospital. The high-tension transformer, filament transformer andX-ray tube are all immersed together in atank of oil (see Fig. 17). This system makesthe apparatus absolutely proof against dangersof high tension electric shock. Note the tubeand transformer in the small tank beneaththe couch.

Present-day ApparatusLocalisation of a foreign body is a speciality

in wartime : this is an interesting job andone which calls for accuracy ; it is not justseeing the bullet in one, or even two planes :that is deceiving. Imagine a shadow of yourfinger on the wall, then move the lampwhich throws the shadow : the shadow ofyour finger moves. Localisation is done by atriangular method ; the tube must be per-fectly centred so that the central ray goesthrough a definite point ; imagine findingthe exact position of a tiny piece of metalin the eye. This centring with the gas tubefor various reasons was difficult (seeFig. 18).

December, 1944

This piece of apparatus was designed bythe writer when gas tubes were in use ; itwas attached to the tube box with a hingejoint and could be swung out of the way.One had to find the point where .the cathodestream struck the anticathode, the pointfrom which the central ray emerged : thisposition varied, it was not always in thecentre of the anticathode. The mirrorbeneath set at the same angle as that of theanticathode, 45 deg., had a centre spot,when the bombardment point of the anti -cathode was centred on this spot : the tubewas perfectly centred, the telescopic pointerbelow continued this line to the desiredposition.

The Navy have carried their own apparatuson ships for many years. It may not begenerally known that certain drugs whichare opaque to X-rays are in considerable use.Organs like the stomach and the gall bladderare not visible by X-rays ; a shadow of thekidney mass is seen, but the structure of thekidney is not. When certain drugs are inthese organs, their internal deformities areusually seen. The drug is not the same foreach organ ; that which is secreted by thekidney is not secreted by the gall -bladder.The stomach and intestine drugs are given bymouth, the latter may he injected as an enema(Fee Fig. 13). The drug for the kidney isinjected into a vein in the arm and finds itsway to the kidney through the bloodstream ;the taking of injecting of drugs gives noinconvenience to the patient. Fig. 19 showsa kidney interior and the drug leaving thekidney on its way to the bladder for evacua-tion. The other side is not seen so well.

NEWNES PRACTICAL MECHANICS

Fig. 20.-X -ray photo-graphs of the internal organsof two different patients,showing the gall bladder

gradually emptying.Case i (right).Cai4 2 (below).

Fig. 20 shows the gall -bladder graduallyemptying : these are two different patients ;it is obvious that the gall -bladder would not beseen without the drug.

There are many other things one could

write about X-rays, and parts of apparatusexplained. The writer hopes, however,that he has at least demonstrated some ofthe more common advances in apparatus andusage of X-rays.

The R.A.F.'s New Fighter-The TempestHURRICANE, Typhoon, Tempest-these

names express the mounting force andpower of the fighters produced by HawkerAircraft Ltd. The last of these, the Tem-pest, has now measured its prowess againstthe Luftwaffe, and has had a very successfulSeries of exchanges. Its introduction tonormal operations was delayed as it had tobe diverted from the fighter's normal role

ere

Side view of the Tempest showing the finestreamlined fuselage.

to combat the flying -bomb menace in whichit scored nearly 600 victories.

The Tempest, like its predecessors, is asingle -seat low -wing monoplane, designed byMr. Sydney Camm. It is powered with asupercharged Napier " Sabre " engine of2,200 h.p. and has a de Havilland variablepitch four -bladed propeller. Its armamentconsists of four zo mm. cannon guns. Thespan is 4ift. ; length, 33ft. Sin. ; and itsheight, t4ft. loin. with tail tin and oneblade vertical, and 16ft. tin. with tail downand one blade vertical.

Londoners saw this graceful addition tothe Hawker family when Air Defence ofGreat Britain was meeting the full assaultof the flying bomb. Looking somewhatlike the Typhoon, but with the ellipticalwing of the Spitfire, and a high tail finrising from the fuselage in a cure similarto the Flying Fortress, the Tempest was inaction as soon as the attacks began.

A front view of the new

Until the balloon barrage was moved intoKent the new fighters flashed over SouthLondon, circling among the bursts of anti-aircraft fire. Later on they closed in onthe bombs, either at sea or over " bomballey " from the coast to the balloons.

Air Marshal Sir Roderic Hill, Air MarshalCominanding A.D.G.B., flew a Tempest aswell as his own Spitfire on flying -bomb,patrols when deciding on the disposition ofthe fighters and ground defences. He usedto take off from the airfield at which WingCommander R. P. Beamont, D.S.O. andBar, D.F.C. and Bar, and his Tempest winghad met the first attacks and devised combattactics. W/Commander Beamont, who wasa Battle of Britain pilot, and a former testpilot of the Hawker Company, nursed theaircraft through its trials and develop-ment with the R.A.F., and trained hispilots in the handling of this extremely fastnew fighter.

R.A.F. fighter aircraft, showing the four cannon guns and four -bladedpropeller.

84 NEWNES PRACTICAL MECHANICS December, 1944

The Story of Chemical Discovery

The Work of the AnalystHow the Chemist Aids in Safeguarding Our Foodstuffs Supplies

AT the beginning of the last centurychemical analysis was virtually non-existent. True it is that there were

then in use certain rule -of -thumb methodsof roughly .testing the qualities of variouschemical commodities, such as alum, soda,and medicinal salts, but, for the greater part,commercial chemical analysis had hardlybeen thought of, let alone systematised.

There were at that period a few enthu-siastic chemical pioneers, notably BaronBerzelius, who began life as a humbleapothecary in Sweden and ended it as thesecretary of the Stockholm Academy ofSciences, and also the French chemist J. L.Gay-Lussac, who showed a particularinterest in devising methods whereby thenature of materials might be determined.By dint of patient toil and investigation,these enthusiasts, working over many years,gradually brought out reliable methods ofanalysing materials and of determining notonly the nature of their constituents, but alsothe actual proportion of such constituents.

It was J. L. Gay-Lussac, for instance, whoinvented the system of volumetric analysis,now well known to all chemical students, bymeans of which the amounts of certainchemical sulAances present in solution formcan readily be determined. In the main,however, the chemical science of thatperiod was rather more interested in ex-tending its domain' by the discovery of newchemical compounds than in establishingscientific wayS and means for the competentand reliable analysis of its known sub-stances. It was only at a later date thatsystematic chemical analysis began to makestrides-at first almost imperceptibly, butafterwards at a very rapid rate-and thatthe analyst's art succeeded in permanentlyestablishing itself.

Accum, the AnalystOne of the first of the chemists-if not

the first of them-who showed himself to beparticularly interested in the analytical detec-tion of adulterants and impurities in food-stuffs was a certain Frederick Accum, aGerman who was then resident in London.Accum was a curious character. He seemsto have been possessed of a goodly measureof the usual German arrogance and bombast,and eventually, in consequence of his being

detected in the act of mutilating books inthe Royal Institution Library, he had toleave this country rather hurriedly. Never-theless, while he stayed in England, he dida lot of good, if only in view of his callingattention to the enormous amount of. adul-teration which the foods of the period werereceiving.

The adulteration of foods and beverageswas, even in those days, no new thing. Itdates back to the time of the Romans, andmost probably, too, long before then, therebeing several ancient records of clay beingadded to flour and of wines being " le: down 'with various other liquids.

But, at the commencement of the lastcentury, the population of Great Britain had

Apparatus for the analytical determination ofsoda in various materials.

Atrt8th century continental chemical lagr-ZrY, which was 4parentlyused for the testing of medicines. (From an old print.)

very largely increased.The demand for foodwas continually ris-ing, and, since therewere no legal checksupon the purity offoods or materials,the adulteration ofeven the commonestof foodstuffs rose tov e r y high propor-tions. Bread, flour,beer, wines, spirits,spices, cheese, sugar,tea, coffee, and evencommon medicines,seem to have beenhopelessly adulteratedin Accum's day.Wines and beers weretreated with lead saltsto prevent their go-ing sour. " Cheapgin " contained freesulphuric acid to give

Frederick Accum (1769-1838), the first pioneerof foodstuffs analysis.

it a certain pungency of taste, and some ofthe spirit distillers even went to the lengthof putting a little white arsenic in theirspirits in order to promote an irritable and aninsatiable thirst on the part of the drinker.

Death in the PotBread and flour, beside having clay added

to them, frequently contained plaster of Paris,whiting, slaked lime, and even finely crushedgranite, to say nothing of a certain modicumof ammonia and alum to impart whiteness tothe flour.

Frederick Accum, in 182o, published hisfamous book, which he entitled " A Treatiseon Adulteration of Food and CulinaryPoisons, exhibiting the fraudulent sophisti-cations of Bread, Beer, Wine, SpirituousLiquors, Tea, Coffee, etc., and otherarticles employed in domestic economy,and methods of detecting theln."The title -page of the book bore a pictureof a skull in a saucepan, and below it thebiblical text : " There is death in the pot "(2 Kings, iv. 4o).

" Death in the Pot," as the book (andeven its author) were nicknamed, had alarge and a ready sale. It was the `world'sfirst treatise on " commercial " analysis, deal-ing not only with the detection of impuri-ties and adulterants in foodstuffs, but alsoin soap, paper, cloth, paints, drugs, andother common commodities.

Accum, too, heightened his reputation (andthe dislike in which he was held in certainquarters) by actually publishing the names ,

of manufacturers whose products he hadproved to be adulterated. As a result hemade many enemies, and there is little doubtthat the commercial world of the time wel-comed his hasty return to his Fatherland,where, incidentally, he obtained a Chemistryprofessorship.

Frederick Accum, with his " Death in thePot " and other chemical revelations, shockedthe public conscience in England. He alsomanaged to stir up the interests of thepioneer chemical analysts. Little by littlevarious Parliamentary Acts were broughtinto being, eacal one aiming at the suppres-sion of certain types of food adulteration.For example, the Bread Act of 183o pro-hibited the use of alum in flour, whilsta second )3read Act six years later extendedthe prohibition to other types of adulteratingmaterials.

It was not, however, until 1872, that thefirst of a long series of Food and Drugs Actsissued from the Parliamentary Houses ofWestminster. Vested interests against all suchenactments had often been particularly viru-lent, and the community in general seemedto have little realised the enormous import-ance of an uncontaminated food supply.

December, 1944 NEWNES PRACTICAL MECHANICS 85

Test papers showing lead stains derived fromvarious trade commodities.

The Official AnalystIn 1875 local authorities were compelled

by law to appoint at least one analyst ofthe highest qualifications. Thus entered theanalyst into the service of the community,a service in which he has assiduouslylaboured ever since.

While chemical analysis is necessarilyfounded upon the most exact chemicalscience, it still remains in many respects anart. Many individuals who may be quiteexcellent creative chemists and researchers failhopelessly at intricate chemical analysis simplybecause they lack the patience, the peculiardeftness of manipulation, and the requisitekeenness for the detection of the unknownsubstance, adulterant, or impurity which theymay be engaged in tracking down.

Even after a century of chemical analysisthere are still many imperfections in thisbranch of science. The notion that it ispossible to " analyse anything " is totallyerroneous. True, in the majority of in-stances, the analyst can always arrive atan approximate assessment of the ingredientsof a material, but he cannot always ferretout the exact truth. There is, for example,a famous proprietary sauce which has beenon the market for many years, and which ismade from a secret recipe. This materialhas literally defied the efforts of severalanalysts to determine its exact constitution.Several other trade products fall into a similarcategory, although, needless to say, theirnumber tends yearly to become smaller andsmaller.

Iodine TestBroadly speaking, the analyst works by

means of a systematised summary of theproperties of all known chemical compounds.His training has taught him that mostchemical substances have specific reactionswhen treated with certain reagents. Thus,for example, if starch is treated with iodine,it will give an intense blue colouration.This forms the famous starch -iodine test,and so delicate is this reaction that it willreveal the presence of as little as o.000000sgram of iodine.

Generally, therefore, any single substancecan have its presence revealed by making useof some specific chemical deticting reaction,and frequently enough, by arranging forthis reaction to proceed under conditions ofgreat accuracy, the actual amount of the sub-stance ir question can be determined.

Of recent years an entirely new systemof chemical analysis has been devised. Thisis "micro -analysis," of which so 'much isheard nowadays.

Micro -analysis is nothing more nor lessthan a modification of the older and now

classical " methods of chemical analysis.In micro -analysis the analyst utiliges a dropof liquid on a microscope slide or a spot ofunknown material on a filter paper. In

consequence of the discovery and intro-duction of new chemical compounds whichare capable of giving highly characteristicreactions even in the state of extreme dilu-tion, it is possible to analyse the contents ofeven a single drop of a fluid. And, by likemethods, it is readily practicable to analysethe ink with which a document or a letterhas been written.

The art of the analyst-as distinct fromthat of the mere chemical works " tester "-is nowadays applied in every large industry.Without chemical analysis technical controlon industrial processes would be impossible.And likewise, without this extremely im-portant chemical art, the purity of food-stuffs and medicines could never be assured.

Detecting ArsenicAt one time a very common adulterant

used to be arsenic. Arsenic is a widelydistributed element. It is apt to get intosulphuric acid which has been made fromiron pyrites. And since sulphuric acid isused in a large number of manufacturingprocesses the greatest vigilance has constantlyto be taken to see that the pyrites -derivedarsenic does not obtain entry into the manu-factured product.

The microscopic investigation of food materialsis part and parcel of the work of every Public

Analyst. '

Some years ago a " beer scare " arose.People who had drunk a certain brand ofthis beverage suffered from the distressingeffects of arsenic poisoning. Analysts foundarsenic in the beer. The ouestion then aroseas to how it had obtained entry into theliquor. It was eventually found that thebrewers had used a certain type of manufac-tured sugar which had been treated witha pyrites -derived sulphuric acid. Thearsenic, originating in the mineral ironpyrites, had found its way into the sugarand thence into the ale.

In another more 'recent instance an analystfound that a manufacturer had unknowinglybeen using pure white arsenic (arseniousoxide, As,O.;) as the, dusting powder for hisboiled sweets inst,..ad of an innocuouspowder, the purpose of which is to keep thesweets from sticking together. It was onlyafter one or two fatalities had occurred thatthe incident was legally dealt with.

Marsh's TestArsenic is, fortunately, an easy element

to detect. The underlying principle for itsdetection is based upon the celebrated testdesigned by J. Marsh as far back as 1836.If into a bottle generating hydrogen gas frompure zinc and pure hydrochloric or sulphuricacid we introduce a little of a material con-taining arsenic, a small quantity of hydrogenarsenide (arseniuretted hydrogen) will be

generated also. This hydrogen arsenideis intensely poisonous, its discoverer,Gehlen, being said to have lost his lifethrough breathing merely a few bubbles of itin its pure state. Hydrogen arsenide is anunstable gas. If it is even gently heated itdeposits its arsenic on to the heated surface,and often enough, if the surface be a glassone, the deposited arsenic takes a mirror-likeform.

Such is the basis of Marsh's test forarsenic. The hydrogen generated in thereaction bottle or flask is passed through agently -heated glass tube. If any hydrogenarsenide is mixed with the hydrogen, thearsenide is decomposed on contact with theheated walls of the tube, depositing itsarsenic in the form of a silvery mirror.Very minute amounts of arsenic can be deter-mined in this manner.

Another common contaminating impurityof a large number of materials is lead. Now,lead is a cumulative poison. It tends toaccumulate in the human system until itreaches a certain concentration, after whichit gives rise to symptoms of slow poisoningwhich are often difficult to get rid of.

White lead used to be a common adulterantof various foods, for this material is heavy,and, in admixture, substantially increases theweight of materials. Red lead, too, onaccount of its weight and colour, has intimes past been used extensively as anadulterant in the composition of various typesof sweets.

Mustard Sets HardNot se many years ago household mustard

was adulterated with dandelion and tur-meric root, china clay and plaster of Paris.Indeed, it is on record that a sample ofcommercial mustard when stirred into apaste with water set hard within a fewminutes, owing to its excessive plaster ofparis content !

Tea, coffee, and particularly cocoa andchocolate have all received the attentions ofthe public analyst ir, their turns. Here theanalytical process is more microscopical thanchemical in nature, for the adulterating sub-stances lay side by side with the genuinematerial and thus are easily revealed bymicroscopic examination.

Chocolate is obtained by grinding cocoa" nibs," which latter constitute the crushedkernels of cocoa beans. The nibs containmuch more natural fat (cocoa butter) thando the shells. of the cocoa bean. Consequentlythe price of the nibs is normally about tentimes that of the shells. Hence the oncenot unfrequent practice-which microscopi-cal examination invariably disclosed-of

Marsh's test for arsenic. A portion of the,substance containing arsenic is placed in aflask along with pure zinc and pure hydrochloricacid. Any traces of hydrogen arsenide gaswhich are generated are decomposed on passingthrough the heated glass tube, with the formationof a silvery film or mirror of pure arsenic on

the interior sides of the tube.

86 NEWNES PRACTICAL MECHANICS

adulterating the true chocolate from the nibswith powdered cocoa bean shells.

Egg and Baking PowdersEgg powders and similar domestic articles

are a form of food which have received muchattention, even in our own times, frOm thecommercial adulterator. It was once commonto adulterate .an egg powder or a bakingpowder with crude soda, and even sand hasbeen revealed in these commodities. So, too,have jams and pickles from time to time.been the recipients of the adulterator's atten-tions. The inevitable arsenic has beenallowed to find its way into jams ; pickleshave had copperas, and even sulphuric acid,added. to them in order to increase theirpungency.

Cheese has not been absent from the list

of, adulterated foods. In one noted case aSurrey analyst found that certain deliveriesof a Gorgonzola cheese had been coated witha mixture of barytes and tallow, barytesbeing a barium compound and highly poison-ous once it is converted into a solublecompound.

Butter'," and even margarine, .have fromtime to time been adulterated, not only bythe admixture of cheap foreign fats, butalso by the incorporation .of such thingsas salt, waterglass, .starch, calcium chloride,flour, gelatine, and paper pulp.

In general, the tendency to foodstuffadulteration, apart, of course, from theproducts of reputable and well-known manu-facturers, is still with us, whilst the adul-teration of non -foodstuff commodities is,unfortunately, often more prevalent.

December, 1944

With increase of scientific knowledge andscientific aptitude on the part of unscrupu-lous manufacturers and producers the perfect,.tion of the practice of adulteration tends toincrease. Yet, at the same time, the vigilanseof the analyst from a technical standpointand the official recognition and extension ofhis sphere of operations is also increasing,so that in this 'commercial war between theanalyst and the adulterator it is usually thelatter who ultimately retires from the contestvery much the wiser for his misdeeds.

In our days, thanks to the work of theanalyst, assisted by a code of legal enact-ments, it is seldom that any really flagrantand large-scale case of foodstuff adulterationrears itself up to shock the opinions of thepubic.

Britain'sNew

WeaponAMONG

the equipment with which theBritish Army blasted its way into

France, and which it is now using, are flame-throwers. Chief among these are the " Life -buoy," a man -carried weapon, the " Wasp,"a light armoured weapon, and the

Crocodile," which is fitted to a heavy tank.

(Above) A " Wasp " light armoured flame-thrower shows its sting when attacking pillboxes.

The Churchill " Crocodile " is the mostpowerful weapon flame-thrower in the worldto -day. With its special fuel it shoots a flamethat is terrifying and deadly. This weaponwas designed to blast the strongpoints of theAtlantic Wall and Hitler's " Fortress Europe,"and it has saved the lives of our infantry incarrying out these tasks.

When this war broke out the Germanshad new and improved flame-throwers. Wehad none.

Flame-throwers were first used by Britishtroops in the Dieppe raid. With them theCommandos put a coastal battery out ofaction. ThOse were the " Lifebuoy " typeof throwers-man-carried.

(Left) A Churchill " Crocodile" rolls forwardwith flame belching towards its target.

" Crocodile" flame-throwers going into action.

December, 1944 NEWNES PRACTICAL MECHANICS 87

A Circular-saw BenchConstructional Details of a Serviceable Tool

for the Amateur's WorkshopBy J. W. COLE

THE saw bench described below costslos. for materials and 4s. 9d. for a 6in.saw. It cuts up to tin. wood easily,

and will do grooves and rebates accurately.If required, a sliding and cutting off fencecan be added, made on the same lines as theordinary fence described. The constructionallows the saw to be built into a workbenchif desired, and this would eliminate the mainframework altogether.

Main )frameThis is built entirely of tin. x 3/16in.

angle iron, fastened together with !in.Whitworth machine screws. The Tin. up-rights have holes tapped to receive them.The slotted top plate is screwed down to theangle iron with 3, r6in. countersunk screws.Extensions of the top longitudinals carry a/in. steel rod on which the fence lockingblock slides. The ends of the 4in. rod areturned down and threaded ;,` in. B.S.F.,and held by nuts as shown in Fig. 2. Thebase angle irons have holes for screws tohold the sawbench down on a table or bench.

Sliding FenceA steel block tin. x tin. x tin. slides on

the lin. round rod at one end of the bench.

A length of tin.3 t6in. angle iron,screwed to this block,constitutes the fence.The steel block isslotted so that alocking screw canpinch it on to theguide bar. The lock-ing screw is extendedwell above the fenceto permit tighteningby a removabletommy-bar. It shouldbe noted that thesliding block must beexactly level with thetable top, and thefence must be parallelto its edge. The fence can beof the table if required.

Tilting FrameThis gives height adjustment without

clumsy tilting of the table top itself. Fig.

6" Dia. 11711(i11111/111677fr

difoo,di.v

/4"

Fig. 1.-Side elevation of the circular -saw bench. (Saw guard omitted.)

The finished saw bench, showing the saw guard in the raised position.

swung clear

the3

shows the main features, tin. X 3;i6in. angleiron again being used. The wide end of theframe has two brackets contrived by cuttingaway part of the angle -iron and bendingthe resulting " tabs " until they are paralleland a nice fit inside the main frame members.A tin. rod completes the hinge. The narrowend of the frame has similar tabs carrying themoving bar shown in Fig. 4 ; this bar is tapped5/16in. Whitworth and has ends turneddciwn to I in. The upper end of the 5/ thin.Whitworth adjusting screw turns freely ina similar, but shorter fitting, arranged betweentwo tin. pieces of angle -iron screwed to themain frame -upper cross member. Thephotograph makes this clear. A milled tin.nut as shown is used to make adjustments.The overall length of the screwed rod is6/in., which enables the saw to be raisedfrom o to 2in. above the table.Saw Arbor

This runs in lin. bearings, but the centralpart is sin: diameter to match the hole in thesaw. Part of this is threaded lin. B.S.F.(right-handed). Arranged as shown, if thesaw is running clockwise (see Fig. 1), thenthe saw nut will have a tendency to tightenas the saw meets increasing resistance. Thisis important for safe operation. Two tin.washers, in. thick and accurately turned,support the centre of the saw and grip it

8"

Fig. 3.-Plan of the tilting frame with saw and driving shaft in position. Fig. 2.-End view of bench, showing the rod for guiding the fence.

88 NEWNES PRACTICAL MECHANICS December, 1944adequately. A collar and split pin keep thearbor in place.

BearingsThe original bearings are brass, ',in.

diameter bushes arranged to swing betweenpointed set screws set in pieces of angle iron.This gives self -alignment (see photograph).Alternatively, plain bearings with flat bases,as shown in Fig. t can be used. Care must betaken to secure true alignment. The bearingscarry cycle lubricator caps.

Saw GuardBehind and in line with the saw a hinged

1

I"

Ait

119,411M111,101,111matiffiliqu nnuuitNnmtlpOnlnitlnwupuiim

It/

s'

?41

Fig. 4.-Details of the screwed adjusting barfor the tilting frame

metal plate acts as a " splitter." It is slightlythicker than the saw cut, and carries the hollowguard, which hinges so as to raise freelywhen the wood goes under it. It will be seenthat the splitter is tilted back temporarilyto raise the guard clear of the saw while itwas being photographed. The guard can beremoved if required.

OperationA a h.p. or h.p. motor drives the tin.

pulley by means of round tin. belting. Asaw spindle speed of 2,000 to 3,000 r.p.m.is suitable.

Colour Photography -2Notes on Distribution of Colours, Exposure Times, and Indoor Work By JOHN J. CURTIS, A.R.P.S.

READERS who have become inter-ested in this all -absorbing branchof our hobby, and have decided to

eventually try making a few exposures on acolour film, will have gathered sufficientinformation to understand that the wholeof the work differs in many respects from"'ordinary " photography, and requiresconsiderably more care throughout the pro-cessing, from the time when the film is beingplaced in the camera, to the final stages ofdrying, masking and mounting of the trans-parency.

You are going to use a film which is theresult of scientific research extending overmany years, and which has been producedby skilled operators using the best ofmaterials and particularly fine machinery.You can be assured that you have got some-thing which is as near perfect as possible,and which is capable of good results, butyou can also be sure that without yourquota of care it is possible to make mis-takes, and thus fail to achieve what themakers claim. -

It is to help you to avoid mistakes thatI am going to mention one or two ratherelementary but necessary details of a pre-liminary nature. Before loading the cameragive it a gentle cleaning to remove any dustwhich may have found a resting 'place in theinside, on the back, or in the slides, andmake sure that the working bench is alsofree of this, for dust, as a rule, is opaque, andspots caused by it on the negative ortransparency are difficult to remove. Load-ing should be done in the dark because theemulsion is sensitive to all light and, if youare using cut, flat films, avoid fingeringthe emulsion side, as this is very delicateand easily marked. It is necessary to usethe opaque shield on the index window atthe back of the camera ; one of these issupplied with each film or spool, and thismay mean that you will have to calculate howmany turns of the knob, or lever, are requiredbefore making the next exposure.

Some colour films require special filters,provided by the manufacturers free, but forthe Dufay roll film Di the necessary filteris incorporated in the emulsion, according tothe makers' instruction book.

Distribution of ColoursIt would seem rather unnecessary to make

any suggestions on what to take, neverthe-less, a few hints may serve a useful purpose.Those of you who have seen colour films atyour local cinema may have noticed that theoperator, when taking the film, has avoidedtoo much prominence to any one outstand-ing colour, prefering the subject to be onewhere there is a general and harmonious dis-tribution of several colours. When takinglandscapes Nature generally finds its ownremedy either by a variety of colours or

tints, or by shadows, but where a skyappears as part of the picture, try to includesome, or at least one cloud. It is better towait for such to appear rather than toexpose on a perfectly blue sky. Most ofus delight in a cloudless day, but if we areout for a pictorial effect we must avoid" bald heads," even if they are blue. I wellremember examining some colour trans-parencies taken en the west coast of Ireland:delightful sea and rock studies, but out ofabout a couple of dozen there were onlythree with clouds, and it was the cloudswhich made these the best of the set. An-other instance of this character occurredin a collection made by a very keen gar-dener ; first came some still life work ofcut flowers in vases, bunches of scarletgeraniums, mauve iris and peonies, all ofwhich were very nice, but not so beautiful asa bowl of various coloured roses and anotherof primroses where the yellows of the flowersblended harmoniously with the greens andbrowns of the leaves. Let the subjects bewell lighted, but hard contrasts must beprevented or avoided.

Let us now give some thought to the veryimportant question of exposure. For boththis side of the subject, and for the proces-sing details, I am only going to write aboutthe Dufay colour roll film ; no doubt all theother makes of colour films and plates givejust as good results, and no doubt theyhave similar characteristics as regards ex-posure and processing, but there may bedetails incident to each, and therefore it isbest to keep to the one make while advisingthose who intend to use any other to be sureto read the intructions given by the makers.

Exposure Times.w.,,The first question which naturally ariseson this point is " HOW do colour films com-pare with others ? " The makers tell usthat the Dufay requires approximately twicethe exposure as would be: given when usingan ordinary roll -film, or four times that forroll -film of the chrome type. Is an exposuremeter of any use with colour work ? Theanswer is yes, especially if you have areliable one, and are familiar with itsworking or recording ; obviously correctexposure is essential, and any means youcan adopt to ensure it is an asset. Wouldthe preponderance of any one colour demanda variation from what would be considerednormal exposure ? When calculating alwayswork for correct exposure of the highlights,and this would be right for shadows and thecolours, but care must be taken to avoiddense shadows and strong highlights. Ifcolour dominates the shadows it might benecessary to increase the exposure slightly.Under this heading it is as well to note thatthe makers state that in colour photographythe correct exposure remains the same

whether the subject is relatively near to orfar from the camera, and whether or notthe subject includes shadows.

To give you an example of the variationof exposure times, a beach and sky sceneat midday during the months of May toAugust, using the lens set at F5.6 wouldrequire /tooth, while all outdoor subjects,other than beach scenes, on bright days withthe sun obscured, wouicl want 1/25th, andif the day was dull, I/loth would be neces-sary.

Is it possible to use any after treatmentto compensate errors in the exposure ?Under -exposure tends to give hard con-trast ana dense results, and over -exposurelowers the contrast and produces lightcolours. For the former, reduction can takeplace during the processing as recommendedby the makers, or after the film has hadits final washing. Intensification can bedone by any of the recognised formula,although the mercurial bath is advised, andis applied when the other work on the film iscompleted. Attempts at correcting exposureerrors can never produce as good a resultas would correct exposure.

Use a large aperture wherever possiblefor obtaining good transparencies, as it isnot wise to stop down except to obtain depthof focus.

Indoor colour photography is possible,but very little practical information can begiven, as there are so many factors to beconsidered ; lighting, surroundings, subject,etc., but one or two experiments will providegood data for this work, and if you use anelectric meter you are advised to read thisby exposing it to a sheet of white papertill the maximum reading is reached at abouta foot from the paper, and then to multiplythe time by 4o. This applies to the use ofhalf -watt or photo floodlight, and with theright compensating filter. The factor for theD3 material is to, and not 4o, so that usersof the roll fiLns will recognise that this isfaster than some of the other grades, anadvantage for both exterior and indoorexposures.

Having exposed the whole of the film, mayI again remind you that it does not pay totake risks, and sot, before opening the backof the camera to remove the spool, see thatall light is excluded from the darkroom, evenfrom the crack under the door. It is alwaysa good plan to well wrap a spool whenremoved from the camera, and for thisreason I seldom destroy the piece of leadfoil with which the Dufay films are wrappedoriginally ; it prevents any dust or lightgetting to the film.

(To be concluded.)[The Thames plate mentioned in the

previous article was riot made up of ruledlines, as stated, but of red and green circleson a blue ground.-ED.)

December, 1944 NEWNES PRACTICAL MECHANICS 89

Inventions ofUniform PeelingSEVERAL devices have been proposed to

facilitate the peeling of potatoes andother vegetables as well as of fruit.However, it seems it has not been easy toremove uniform external layers from objectsOf varying sizes and shapes.

A prospective holder of a patent in thiscountry asserts that he has discovered anefficient peeling device. His method pro-duces the progressive rotative treatment ofthe surface of an object by which thecutting means may advance as required byshape and size rather than at the rate ofpredeterinined relative movement betWeenthe object to be pared and the support fo?the cutting means. He is thus able toremove a surface layer of uniform charac-teristics from vegetables and fruits of differ-ent size and shape.

His paring apparatus comprises thefollowing features :

Rotatable object-supporting means ; thereciprocable carrier ; means for rotating thesupporting arrangement and advancing orreciprocating the carrier simultaneonsly inpredetermined relation ; a cutter effective inremoving the external layer of the object as itrotates ; and a pivot for connecting the cutterto the carrier for travel in an arc in a planePractically inclusive of the axis of the sup-porting means. As a consequence, the cutteris given a retarded advancement wheneverits path varies in relation to the course of thecarrier.

Folding Shoulder Butt

jkCURRENTapplication for a patent in

this country concerns stocks for fire-arms of the class intermediate between theautomatic rifle and. the pistol.

One object of the invention is to providea shoulder butt which can be folded on dieunderside of the weapon, the butt beingextensible at will. Further aims are toimprove the sighting arrangements and tomodify certain parts of the firearm withoutimpairing its efficiency consequent upon theimprovements.

The foldable shoulder butt is detachablyfitted to the rear casing of the firearm. Itconsists of a triangular device in which alight metal strip framework constitutes the'upper and shorter side, and a like frame-work the lower and longer side. Both sidesare hinged to a common base plate forminga shoulder rest. The forward ends of theframework sides are so hinged to the stockor casing of the firearm that the longer sidefolds within the shorter side and base inthe inoperative position.

The folded assembly is nested againstthe underside of the casing whilst permittingthe trigger to act. Automatic locking devicesare furnished to secure the folding butt ineither its operative or inoperative position.

The use of a butt stock with this class ofweapon enables the back sight to occupyapproximately the customary rifle positionin relation to the distance from the eye.

To facilitate the use of the weapon whenthe butt is folded, the trigger mechanism isplaced somewhat to the rear. There are atrigger guard and trigger casing side platesprotruding below the hinged butt memberswhen in the folded condition.

Plastic Laundry -marksTO identify articles sent to the laundry it

is a general practice to print marks onthe articles in an inconspicuous place. It

By "Dynamo"Interest

appears that another method is to use identi-fication tabs, some of which are made ofcloth and sewn to the article,, while othersconsist of metal and are clamped to thefabric.

Yet another practice is to sew identifica-

The information on this page is speciallysupplied to " Practical Mechanics " byMessrs. Hughes & Young, Patent Agents. of7. Stone Buildings. Lincoln's Inn, London,W.C.2, who will be pleased to send free toreaders mentioning this paper a copy of theirhandbook, " How to Patent an Invention."

tion figures or letters directly into thearticle.

Having reviewed all these methods, aninventor asserts that none of them is satis-factory. He contends that permanent black

As a protection against scurvy and other diseases, soldiers in the BritishArmy carry in their tunic pockets a small tin box containing abouttoo white tablets containing vitamin C. This substance is contained inthe juice of lemons, limes, oranges and fresh vegetables'. Scores ofchemical factories now produce an artificial vitamin C, which is in everyway identical with the natural product. Our illustration shows some

vacuum evaporators used in making vitamins in huge quantities.

marks disfigure the articles and that thesame objection can be made to the sewn -on tabs and the sewn -in identification marks,as they cannot be removed.

In the case of metal tabs, which can beremoved, he mentions that these tabs oftenbecome entangled or torn from the material

in the course of washin.g. They also wearout the fabric.

To overcome these disadvantages, theinventor has devised the following means:

He proposes a tab containing or consist-ing of a thermoplastic material which is notsoftened at roo deg. C. but is softened at atemperature well below the scorching pointof texile material. By heat and pressure itmay be attached to the latter, which is easilyaffected by heat-for example, artificial silk.On the face of this are identification markswhich are easily removable by tearing offwithout injuring the fabric to which theyare attached.

In one application of the invention a finelywo'ven fabric, such as cotton, serving as abacking, is coated on one side with thethermoplastic material. If desired, morethan one coating may be applied.de

The the tabwhich is not to beattached to the articleis used for the identi-fication mark.

Anti -draught DoorsTHE swing door

has been occupy-ing the attention ofan inventor. In hisapplication to t heBritish Patent Office,he comments uponthe disadvantages ofthis oscillating portal.Remarking that, as ameans of draught ex-clusion, the revolvingdoor is effective, headds that it has beenobjected to on theground that, in theevent of a panic, thethoroughfare is inade-quate.

The usual form ofswing door, he con-tends, is draughty asa result of its con-s t r pc t io n. Thisdraughtiness is aggra-vated when, as some-times happens, aswing door fails-o w in g to faultysprings or other cause-to return tc, its nor-mal position of rest.

The inventor hasaimed at rendering aswing door draught -proof when it isclosed, whether it isin or somewhat out ofthe central plane ofthe door -frame post.

According t o hisinvention, that partof the frame or postwhich is adjacent tothe free edge of thedoor is curved (e.g.,as an arc of a circle)

and has a dimension in the direction ofmovement of the door greater than thethickness of the door. In addition, draught -excluding rubbers are provided along thefree edge of the door, and, if required, aboveor below the door, or in both positions, iffound desirable,

90 NEWNES PRACTICAL MECHANICS December, 1944

The StreizAth of MaterialsA Modern ScientifiO Mystery Outlined

THEfact that a steel bar ought, in

theory, to be about'a thousand timesas strong as it really is constitutes, at

the present time, one of the first-class mys-teries of modern science.

Despite the production of our high -tensilemetals and other super -strength materials,it does seem that we are, in actual fact, com-pelled to utilise very inefficient materials forthe construction of our modern world.Thanks to patient investigation by means ofX-rays, we know quite a lot about theinner constitution of solid materials, eventhough this knowledge falls considerablyshort of what, we should like it to be.However, we are aware of the general planupon which the atoms of solid materials arearranged. We know, particularly, how they -are positioned and spaced in a sort of three-dimensional -network or " lattice," and wehave a good idea of the actual distancesapart of the atoms constituting a solid sub-stance, for modern X-ray work has madeit possible to measure the positions of atomsto within a millionth -millionth of an inch,which is a dimension about ten million timesmore minute than the diameter of the small-est particle which can be discerned underthe most powerful visual microscope.

With this intimate knowledge of atoms insolids it is possible to calculate the inten-sity of the forces which bind atom to atomin the solid structure. And it is just herethat the astonishing fact is revealed that allsolid materials seem to be enormously weakerin tensile strength than they should beaccording to the theoretical calculationswhich can be made on them.

Steel, for instance, ought, in theory, tobe several hundreds and, sometimes, even athousand times as strong as it is. Copper,tin, brass, and non-metallic substances suchas glass, pottery, and the like ought, like-wise, to be hundreds of times stronger thanthey are actually found to be.

What, therefore, is the cause of this basicdiscrepancy ? It cannot be ascribed toerrors of observation or calculation. Norcan it he due to the adoption of falsetheories, for the existence of individual atomscr material particles within solid materialscan be proved up to the hilt.

Inhibiting FactorThe only inference is that there exists

some factor or factors concerned with thegeneral structure and make-up of solidmaterials which strongly inhibits the cohe-sion of atom to atom, or, rather, of atomiccluster to atomic cluster. It seems certainthat if this strange factor were not operativethe tensile strength of solid materials wouldbe vastly increased. Lightweight bridges,super -lightweight aircraft, and ultra -lightbuilding structures would at once becomepossible, bringing with them not onlyincreased efficiency of design, but also verygreat saving in actual material. Boilers andother pressure -vessels could be made verymuch stronger for the same mass of material,a feat which would at once result in aconsiderable increase in mechanical powerof prime -movers and other devices.

The vast discrepancy between the observedand the calculated tensile strength of a solidbody has introduced to modern physicalscience a problem of the first magnitude. Atthe moment it is essentially an unsolvedproblem, and it has remained such for abouta dozen years. In a way, this strangeweakness of metals and other bodies con-stitutes one of the " hidden " problems ofscience, for its investigation is anything but

spectacular in nature, and progress with it isalmost disappointingly slow.

When the late Sir William Bragg, togetherwith his son, Professor W. L. Bragg, com-menced their now classical work on the

A microscopic view of the fractured cross-sectionof a thin steel member which broke underintermittent stress. The crystalline nature ofthe metal and the " hills and dales " of itsfractured surface are well discernible, showingthat the metal must have fractured along

definite lines.

o4,-4,siolook--,...........0.- .4,11- Itfi,.... IA.* ,oll,

j 0iik ilk° 0. oilk 10.0 * 01' ik" it.

1 41/x. .11 0 Ill 0. II. 11 11 1111

.0 O. 0. 0° 0° 0° 00 40%0' 11011,1141,010. .01110400100 ,0 of *O. 01 0 0. lie ^0 0%110I. 0..0.+4O*** . II. it. ,01, 00 010 .0 0- 0-:iVillik10:140110°10, "gee. 0:0t 01°0.00

tiAlV*411kAZWIMIVO. 01.4 loiito 0 0 1

.4'140 ob"- 0 .0%** 0 I ,:o 4*. iii;1kik .. O.% 0: 4 %It i0: 0 1:0% Ifige

i441g10110.1:41A1AAP411S **It' .14.010 4:0' esI0 l' 4 0 01 0. 0. O. 10.-.4

alk. AL 0 di, .0 0111 ' VP' Ow 0. 040.* 11. 01

al 11:141 :I it.:1144 40.1P:14 1.1611 !.:1 0.4t k.:1 1:::: 11:4. :4 ":I I::: :- - -A flaw in a wire mesh which represents theweak spot of the mesh and is likely to growin extent. In a somewhat analogous manner,flaws in the ranks of atoms constituting solidmaterials tend to " grow " under stress and areresponsible for certain types of tensile weakness.

X-ray investigation of crystals, practicallynothing was known about the interior con-stitution of solids. Because the atomicdimensions existing within a solid are smallerthan the wavelengths of visible light, it was

clear that we could never hope to penetratethe secrets of solids by means of any con-ceivable system of ultra -microscopic investi-gation. But the Braggs, using the X-rays,which have wavelengths ,much more minutethan those of visible light, were enabled,by' means of a system which they evolved,to measure the amount of scattering whichX-rays underwent on contact with a crystalsurface, and, by this means, to demonstratethat the constituent atoms are all arrangedin definite order or pattern in rows ofdefinite 'thickness, with each individual atomor particle situated a certain definite distancefrom its neighbour. It was, as we havealready seen from such investigations, thatthe theoretical strength of metals and othermaterials ultimately became calculable.

Griffith's Glass FibresSomewhere about the year 192o, Dr. A. A.

Griffith, of the Royal Air Force labora-tories at Farnborough, happened to noticethat freshly -drawn fibres of silica or glasswere stronger (about 5o times stronger)than similar fibres which had been drawnfor some time. It appeared that such fibresrapidly developed their characteristic weak-ness after having been drawn.

Griffith, although he was engaged onother work at the time, interested himself inthe problem, little thinking, perhaps, that hewas setting the ball rolling in respect of thewhole mysterious problem of solid strength.He put forward the notion that the weaknessof his glass and silica fibres was due to someinterior disturbance of the individual atomic'particles of these articles. The fibres, saidGriffith, were composed of a strong surfacelayer and a relatively weak core, the latterbeing due to the existence of interior crackswithin the mass of the material..Griffith's original theory was found to be

untenable. Not very long afterwards Pro-fessor A. Joffe, then of the Physico-Tech-nical Institute, Leningrad, carefully prepareda thin, parallel -walled glass rod which hesubjected to a very delicate tensile test.During the performance of the test he sur-rounded the rod with dilute hydrofluoricacid, which dissolved away its outer surface.Joffe found that the strength of the `rodincreased about five times, from which ex-periment he concluded that the weakness ofthe rod lay in its surface rather than in itsinterior, as Dr. Griffith had originally sup-posed.

Other workers showed subsequently that asilica rod having a freshly prepared surfacecould absorb traces of both water andalcohol, and that this absorption resulted inits becoming weaker.

Joffe's ExperimentsThe Russian professor Joffe, confirming

these experiments, took crystals of rock saltwhich he tested for mechanical strength.By performing his tests with the crystalsimmersed in warm water he found that theapparent strength of the crystal increasedmore than 16o times. Here again, stressedJoffe, was a case of a material suddenlyincreasing in strength after its outer surfacehas been removed.

From a large number of varied experi-ments such as the ones described above,Joffe put forward the explanation of solidweakness which has come to be at leasttentatively accepted at the present day.Joffe's notion was that the entire mass ofa solid body invariably contains a largenumber of sub -microscopic flaws, the exact

December, 1944 NEWNES PRACTICAL MECHANICS 91

nature of which he could prove very littleabout. The more of these flaws a metalcontained, the weaker it was.

On this assumption, Professor Joffebrought forward the idea that the bigger thetest specimen the more flaws it will be likelyto contain, and consequently the weaker itwill be. Experiment seems definitely to haveconfirmed this assumption, for by testing outa large number of silica and glass fibres,Joffe and his co-workers found that thesmaller the specimen, the relatively strongerit was.

Let us now go back for a moment to thewonderful work of the Braggs on the subjectof crystal structure. By means of their X-raydiffraction methods these two British pro-fessors at London and at Manchester wereable to investigate the interior structure ofa very large number of different materials.They were able to prove beyond all doubtthat certain crystalline forms contain fixedarrangements of atoms positioned in aframework or " lattice," as they called it.In this respect, the arrangement of the con-stituent atoms within a crystal can be likenedto the " pattern " formed by a troop ofservicemen drawn up on a parade ground.

The X-ray MethodThe Braggs' work on X-rays and crystals

enormously widened our knowledge of theprinciples of solid structure. Yet, in one ortwo respects, it led to some disappointment.For, although the X-ray method can tell usall about the constitutional make-up of acrystal or other solid material it cannotinform us if the theoretical " pattern " iscomplete in all respects, or whether thereexists any areas of disruption between theindividual atoms. The Bragg X-ray methodgives us an astonishing knowledge of. atomsin the aggregate, but it tellsindividual atoms.

The X-ray eye which science has givenus to investigate solid structure cannot revealthe absence of one or two atoms here and thereamong the atomic frameWork. Nor can it tellus whether any atoms are permanently out ofposition with regard to their neighbours, orwhether there exists any unusual repulsiveforce between them. There might, indeed,be a deep cleft within the atomic ranks of acrystal without the X-ray method beingable to reveal it.

Sub -microscopic 'FlawsThe present theory (tentative, it is true,

but certainly of working value) concerningthe apparent enormous weakness of metalsand other solid bodies compared with theircalculated strengths, is based on the aboveconsiderations. When a metal or other sub-stance solidifies from the liquid state itsconstituent atoms apparently do not positionthemselves with perfect dimensional regu-larity. There exist gaps, vacant spaces withinthe ranks of the atoms. The individualattractive forces of the atoms are not equallybalanced. One atom may exert more attrac-tion on one side than it does on the other.As a result, it may tend to become perman-ently aligned out of its normal position. Thatis to say, it is nearer to one of its neigh-bouring atoms than it is to the other. Thissort of thing may be repeated deep down intothe material so that there is formed a sortof flaw, crack, or line of weakness in thatdirection. Under these conditions, whenopposing forces act upon the solid material(as they do when it is subjected to tensilestress) the atoms at one side of the flaw -linego one way, whilst the atoms on the otherside of the line are pulled the opposite way.The flaw constitutes the weakest link in thechain. The application of external tensilestress increases the flaw, widens the crack,

and provides the area or plane at which theeventual rupture of the solid material willtake place.

The " laddering " of a silk stocking and thedevelopment of a fault in a wire mesh orsieve are cases in point, for in both in-stances the trouble occurs by the initiation

A photograph showing a flaiv extending or" growing " through a mass of metal. Herethe metal is copper and the flaw has been setup by the intermittent twisting of the metal.

and rapid growth under stress of a singleweak spot.

It is now thought that most solid materials,even, indeed, the strongest of steels, aremore or less riddled with these sub-microscopic flaws which extend through themass of metal and terminateon the surface. It is thesurface flaws which matter themost, because these give riseto the areas of rupture andbreakdown. If the surfaceflaws could be got rid of, theactual tensile strength of thematerial would at once go upenormously.Electrical Sputtering

Microscopic observation ofthese supposed cracks in thesurface of metals and othermaterials has not yet beenmade. Professor Andrade,of the London UniversityCollege, has, however, made anear approach to this obser-vation. By means of a deli-cate method of electrical" sputtering " in a h i gvacuum he has been able todeposit particles of silver orgold on to various objects. Inmost instances he has foundthat the sputtered met a ihas tended to arrange itselfin straight lines on the sur-face of the experimentalobject. Even when the sput-tered metal has been dis-solved off its support and thelatter has been again sub-jected to the same sputteringtreatment, the almost per-fectly straight lines reappear.

The inference here, accord-ing to Andrade, is that theparticles of sputtered metaltend to align themselves in

the invisible cracks, the whole effect beingnot unlike, in principle, the " filling " of thesurface grain of an oak board with a whitepigment in the production of " limed oak."

It has even been possible to obtain a criss-cross of lines on the surface of one varietyof diamond by means of the electrical sput-tering method. However, on another typeof diamond these characteristic lines havefailed to appear, and it is just this varietyof diamond which is the stronger of the two.

It is on the above lines that the initialattacks on the important and far-reachingproblem of solid strength have been madeby individual workers at varying timesduring the last decade or so. The problemis a very tangled, involved and unusuallydifficult one, for it brings to the forefactors which are more or less totallyunknown and which, as yet, can be littleguessed at.

Areas of DisunionWhat seems to be at the root of the appar-

ent weakness of solids is the existence ofnumerous areas of " disunion " {for want ofa better word) among the orderly rows ofindividual atoms making up the solid materialin the mass. It is these lines of weakness,flaw channels, sub -microscopic cracks, orwhatever you like to imagine them as, whichinhibit the solid interlocking of the entiremass of atoms making up the solid material.Hence, when tensile stress appears, someatoms go this way, others go the otherway. The atomic house is patently dividedamong itself. Ultimately, it falls.

Whether the existence of these areas of" disunion or discontinuity is " natural " toall solid materials, whether, under anycircumstances, it is avoidable, and whetherexisting weak areas can be healed up andunited by any possible means are all import-ant problems for the future. At presentwe have no information whatever on suchmatters.

It follows, however, that if, by any means,'the constitutional strength of metals and

- - ------ -An X-ray photograph showing the concentric scattering of theX-ra,ys during their passage through a crystal. It is from astudy of such " patterns that the arrangement of 'atoms insolid materials can be determined. The white line is a silhouetteof the device used for holding the crystal in the path of the X-rays.

92 NEWNES PRACTICAL MECHANICS December, 1944

other bodies could be increased by even 20per cent., a new era in structural andengineering science would be ushered in, tosay nothing of the actual saving in Materialwhich would result.

" Crystal slip," which is the well-knowncause of the more or less common fatigue ofmetals, has, so far as can be seen, little todo with the problems involved in theapparent constitutional weakness of metals,

for metal fatigue only affects those metalmemberS which are intermittently stressed.The rupture or breakdown of metals understeady and prolonged stresses seems to be adifferent thing altogether, although, naturallyenough, this effect may take place concur-rently with the more fundamental effect ofmetal breakdown due -to constitutional weak*ness.

Clearly. however, much original investiga-

tive work still remains to be performed in thedomain of this still perplexing and obscuresubject before the necessary light is thrownupon the matter. The subject was firstseriously opened up about a dozen years ago.It has advanced a little during the interven-ing time but, unfortunately, the day when wecan even prophesy the ultimate appearanceof " theoretical strength " metals is still quiteundiscernible.

steel -framed HousesDemonstration Houses Built at Northolt,rvi the Northolt Grange E s t a t e,

Northolt, Middlesex, the Ministry ofV. Works have erected several blocks ofhouses built of various materials designedto make use of such labour and facilitiesthat are likely to be available in the imme-diate post-war period. These. houses afterbeing open for inspection by members ofthe public and building trades, etc., willafter a period be used for occupation.

The accompanying illustrations give agood idea of the pleasing appearance of twoof the houses of steel -framed construction.The house seen on the right has a structuralsteel frame with ztlih. brick to the 1st floorlevel, sheet steel on fibre board above andtin. lightweight concrete block as innerlining. The house on the left has a coldrolled frame with cement render on steelsheet above, or steel wire fabric to 1st floorlevel, steel sheet above with an inner leaf

1

_

The attractive front entrance of

of plasterboard panels bonded to fibre board.Various other types of houses and flats

have also been erected on this estate, anoticeable feature being the variety offittings. In the working kitchen of someof the houses there are fireclay sinks, someof vitreous enamel, and some stainless steel.In the flatted dwellings the steel kitchenand bathroom fitting, which is installed inthe Emergency Factory -made Bungalow, hasbeen incorporated and cupboards have beenused as partitions between two bedrooms.

Mss'NM

111011

Middlesex, by

AM

one of the houses.

It would be possible to incorporatein house design the cupboard unitsthat are displayed in the flats. Onefeature of the construction of theseflats is the absence of wet tradesabove foundation level. Practi-cally the only wet material usedwas the mortar for jointing theconcrete blocks. Further, theconstruction enables the roof tohe put on at a very early stage,so keeping all internal work dry.

the Ministry of Works

Two of 'the houses built with British Iron and SteelFederation steel frames. As will be noticed, these houses aresemi-detached, the one on the right having brick walls up to

the first floor level.

The electric kitchen in one of the houses.

December, 1944 NEWNES PRACTICAL MECHANICS 93

Cars Designed by the LawIAM one of those queer people to whom

motoring brings not only thoughts ofthe explosion speeds of gas or expansion

ratios, but also of the habits of bees, ants, orany of the delightful creatures which usedto live in the country before lanes wereturned into ordnance workshops. In short,I am very fond of my car, and I miss itscasual use terribly, in spite of an excellentbicycle.

But I read, nowadays, so much unpleasingnews about cars and their appurtenances thatthe words of Col. McLagan, of the S.M.M.T.came as a relief. " The present method ofcar taxation," he said, " will have to berevised so that creative designers can makeautomobiles that will sell overseas." Justso. Larger cars could, in fact, be farcheaper but for a childish law which satis-fies no one but a few short-sightedmanufacturers.

So much else on the motorists' horizonseems bad. First of all " they "-the modernsign of authority in requisitioned h2tels-tell us that peace and petrol go poofly to-gether. I gather that the continent has tobe well supplied with fuel, food, roads, andvehicles, long before " they " will con-descend to remember a little place calledEngland.

The "Microear "The second complaint is that we have

apparently failed to learn the lesson of thelarge-engined Jeep as compared with ourtow c.c. pets, and that we are soon toexpect the appearance of what I must call the" microcar." I also suspect a legacy of warrestrictions which will be unhelpful to trade,and valuable only to the staffs they main-tain.

Now I dislike most small cars. Nearlyalways. It is a personal view, but there areothers who agree, and there are very fewBritish cars to which we can turn. Myexperience of the rather " buzzy " miniatureis that the item of comfort is sadly missing.Being of great age, and after some unex-pected years in the Army, comfort is one ofthe molt important things if I am to followmy country bees in peace. Or if I want tomaintain the highest praise of any transport,sometimes to forget that I ani travelling atall.

Cars, of course, should function uphillwith the same sensation as that of coastingin neutral with the engine " off." And I findthat the ',too c.c., and under, job leavesnearly everything to be desired, except cheap-ness and ease of wheel changing. Silence,smoothness, ease of seating, and effectlessacceleration have all gone.

Nor am I so foolish. For twenty years alarge proportion of the public have beenwilling to pay £300 over and above the costof a car with an identical performance as tospeed and passenger capacity, to receive thevery qualities that we affect to despise.Yet the semi -spring, whining wagon thatwe call " sports," seems likely to win thepeace as the sole result of a system of taxthat might have been designed either by . aprejudiced maker or a professional wrestler.. Some years ago .I made an amusing experi-

ment. With great difficulty I collected adozen non -motorists. These sufferers I drove"round the houses" after blindfolding themmost carefully before leading them to thecars. Two cars I used: one English about18 h.p. very good, another about 25 h.p.American, very " bad." I told my patientsthat one was a Rolls-Royce. All had heardthat name, and after the comparative drives,

By Prof. A. M. LOW

no less than so were certain that the " Yank "was Of that beautiful breed.

I asked them how they chose. " But itwas easy," they said, " it was gliding-wewere not bumped-not so much noise-nogrindings. The latter were bottom gear andnot my gear -changing. Ten out of twelve!And one of the select two said he liked tohear the engine and to feel it was there!

I confess that I must usually buy asecond-hand car. My observations have toldme that, having no ready access to a suitableworkshop where maintenance is free, Icannot keep a small engine in the pleasanttone that alone ensures good behaviour underneglectful periods of use. Nor am I willingto follow an instruction book that has theunparalleled netve to invite attention everySoo or every i,000 miles.

American -type CarsOften I have owned an American -type car.

I reckon that the appalling tax which cheatsme out of far more than is paid by thedriver who can afford to pay four times asmuch, and who covers four times mymileage on public roads, is partly offset bycapital cost. My journeys are not longenough for consumption to matter greatly,an'd I have discovered, incidentally, that themedium " fussy " vehicle often uses as muchfuel as a high geared model of 5o per cent.greater capacity.

If cars must be taxed, and it is quite illo-gical to do so, it seems clear that the moneypaid should be proportionate to use. Sofoolish to bow to any formula which juggleswith capacity. The possible variations of boreto stroke .are not very wide in practice. Anyrestriction on design is bad if we believe,as we are so fond of saying, that regimenta-tion is unhelpful.

How right is Col. McLagan! What mili-tary car is so successful as a Jeep ? Whatcar, over colonial roads, is preferred to thelarge-engined machine ? What Britishmanufacturer has had a chance to competein quantity, experience, or freedom with aBuick or any of its many minor cousins ?

An engine should have plenty of " powerin hand." And this means without excessiveengine speed in an internal combustionengine which is not inherently suited totraction at all. During the war, research hascompressed. years into weeks in the matterof knowledge. Money has been spent likewater on engineering development. We havenew metals, new designs, lighter alloys, farbetter fuels, and production methods thatwere formerly unknown.

Is it too much to hope that these good

PLANT ENGINEER'SPOCKET BOOK

An invaluable work for all engineersresponsible for the installation,operation or supervision of engin-eering plant and equipment in

works and factories.

Of all Booksellers, 6'- net, or by post 616from George Newnes, Ltd. (Book Dept.),Tower House, Southampton Street, Strand,

W.C.2.

things will be freely used without prejudice ?There is nothing clever in compelling awine -glass engine to overwork. The motoris there to provide comfort, as well as tomove itself from A to B., Remember that,not long ago, the spokesman of one of thegreatest American combines said that his" outfit " could switch to car production atfull output within seven weeks from the dateof peace. I read that, in the States, paperand other amusing things are being" released." Does anyone really believe thatmanufacturers are thinking now of swordsinstead of ploughshares ?

The world needs cars. The continent will,have few restrictions of an artificial nature,and I suggest that if we hold up our designs,our driving, and our cars much longer, otherlands will have the same dear old to years'start. It is the red flag days again. Onlyfar redder in more ways than one! TheAmerican Government has just aided a groupof industrialists to visit South America todiscuss the establishment of a plant to pro-duce popular -priced cars. This, I imagine,is quite without significance to our " authori-ties."

Of what use is it to say proudly " after thewar 600 c.c. will do the work of 2,000 C.C.-small cars will carry big loads at 6o m.p.h."We know it. A 900 c.c. car would alwaystake four fat men at 7o-or at least has doneso for some years. If this was all thatmattered, why large engines at all ? Whya colonial market ? Why American carshere in the home of engineering progress ?

My trouble is, no doubt, that I enjoy thesoft, comfort and speed of a -larger car.I cannot get anything like it in England, andit is high time that the design ban wasremoved with blackouts and other disad-vantages under which the countries we shallhelp do not suffer. Surely a few millioncivil servants can devise a better plan thanto say " all cars must be so small that theycannot compete with any others out ofEngland." If it has been possible to restrictpetrol so that doctors who leave their routeby a few hundred yards can be prosecuted,it should not be beyond wit to impose a" user " tax that does no harm to commerce.A petrol tax is so simple that I realise it isunlikely to be adopted.

Thermal EfficiencyThe cult of thermal, at the expense of all

other, efficiency, has surely had its day.Even the myth that " American cars don'tlast " has long since been exploded. I havemany times purchased old " Yanks " for afew pounds. After five years they starteasily, are well sprung, bear huge overloads,are fast without nursing, they seldom needdecarbonisation, and they are not terriblyuneconomical when first cost, depreciationand maintenance are borne in mind.

It distresses me to think that othercountries are now preparing- novelties. Iam sorry that heaters, automatic hoods, self-raising jacks, radio, blowers, and othergadgets should be found abroad. It seems tome that this vital time of " change over "soon to come is a heaven-sent opportunity forus to grasp what politicians call the fruitsof victory. Tiny cars have their great uses.So has good solid heavy British design. Butplease let us not forget that we should nowbe very busy re -planning everything andchanging old for very new indeed. A utilityrechauffee of 1939 in models or laws willnot go far when the improving test of hardcompetition begins again.

94 NEWNES' PRACTICAL MECHANICS December, 1944

Swi tchAear DevelopmentThe Progress Made in This Important Branch of Electrical Science

By J. H. M. SYKES

Fig. 1.-Sectionalised view of a modern metal -clad circuit breakerfor 3 -phase, 5o cycle, 6,600 -volt circuits.

ROM the earliest days when menbegan to use the magic of electricityand to experiment with the incredible

services it could perform, the methods ofcontrolling, and interrupting the electriccircuit presented peculiar problems of theirown.

In the beginning, when batteries andsmall, dynamos were the only sources ofpower, the switch used to break the circuitwas a simple affair. It was not long beforethe knife switch, in the form in which itexists in simple applications to -day, wasdeveloped. The early forms were designedsimply for good surface contact when theswitch was closed, and various manufac-turers developed ingenious designs of spring -loaded contacts, multi -blade assemblies, andthe like, for the purpose.

Later, some provision was made for thecontrol of any arc which might arise whenthe circuit was broken. With the gradualincrease in the size of prime movers anddynamos, it was beginning to be realised thatthe main problem in switchgear design wasgoing to be the control and extinction ofthe arc formed when circuits of greater andgreater inductance and capacity were dis-connected under short-circuit conditions.

The first steps were to make the actualbreak quicker and independent of the speed

of manual operation,a n d spring loadedauxiliary contactsattached to the bladeof the switch wereone of the first stepsin this direction. Butprogress soon. tendedtowards the increaseboth in power and involtage of electricalsystems in all parts ofthe. country, and thechange over to A.C.generation, with itsresultant problems int h e capacitance of

on g transmissioncables, feed - backfrom rotary c o n -vertors, and the like,all of which causedthe switch arc to become more powerfuland uncontrollable than before, made itnecessary, before long, for great &Medi,-nation of designers' thought into the prepai-ation of switchgear capable of dealing withthe conditions the rise of the eleetriCalindustry presented.

For the higher voltages, the obvious stepwas to increase the length of blade, to operateit remotely by an insulated shaft, to speed

up the break by means of more poWerfulsprings, and to place the whole switch in acompartment of brick or 'stone where anyflame or explosion could not harm theoperator. The need for automatic openingon overload became imperative, as the fuse-which had hitherto been the only formof protective device-became so bulky, un-manageable and often unreliable that it couldno longer be the sole source of protectionfor electrical circuits of growing importance.

Automatic TrippingThe industry, therefore, was called on to

design a switch Which would " trip " oropen automatically when called to do so byoverload in the feeder it controlled.,

This meant a radical alteration in thedesign of the actual circuit breaking elementof the switch. It was not long before ageneral" type of design was evolved whichmostly took the form of a tank full of trans-former oil-a thin mineral oil of a highflash point-and in this was immersed thewhole of the switch contact assembly, sothat the arc would be' immediately quenched.The design of this assembly had so far alteredfrom the simple knife switch as to becomea type where the incoming wires werebrought through insulators in the ton plateto contacts mounted on porcelain posts onone side, while the outgoing wires weresimilarly brought into symmetrical posts onthe other side. Incoming and outgoingcontact points were bridged, when theswitch was closed, by a horizontal contactpiece which rose and fell vertically. When

Fig. z.-Typical oil -filled circuit -breaker contact assembly, showing" &plosion pots."

the switch was closed, the insulated oper-ating rods fixed at right angles to the contactpiece were drawn upwards by a linkagemechanism against a powerful -spring, andwere held in the closed position by a lighttrigger called the trip catch ; and this, whenoperated by a simple electro-magnetic devicesuch as a solenoid, allowed the spring todrive the contact -making assembly veryrapidly downwards, drawing the arc through

December, 1944 NEWNES PRACTICAL MECHANICS 95

the oil. . This process is still in use to -day(Fig. r), but every feature of the originaldesign has been developed and modified asthe result of experience. The early designswere to a great extent empirical, and therewere many failures as the amount of powercontrolled rapidly increased (especially asdesigners did not fully realise the extent ofthe enormous electro-mechanical f or c esdeveloped in the conductors during short-circuit conditions). The switch tank andassembly were mounted in steel or concretecubicles with the outgoing cable connectionsat the bottom and the busbars at the top.The handle for closing projected throughthe front cover. When the switch was calledon to break the very large fault currentswhich resulted when the whole of a centralpower station fed into a dead earth on anoutgoing cable, the arc so produced, togetherwith the momentary mechanical stresses, wassometimes sufficient to explode the tank, ruinthe cubicle and cause disastrous fires.

The general trend of progress was towardsstrengthening the tank until it became asit is to -day, a boiler -plate assembly of greatmechanical strength ; to increase the volumeof oil for better quenching of the arc ; to"speed up still further the tripping operationby the use of more powerful springs, moredelicate trip catches, lighter moving partsand careful attention to others parts of themechanical linkage, and to begin to payattention to the actual form and design ofshe contacts themselves so that the arc wasdirected in channels where it could do noharm.

"Metal -clad" PrincipleAnother principle, too, was making rapid

headway. It was the metal -clad " principle,where not only was the switch itself in asteel tank, but its connections to the busbars,And the busbars themselves, were solidlyencased in insulated media of various kinds,and then also clad in metal. This meantthat switchgear was no longer subject tofaults arising from its bare connections, suchas those due to inflammable gases arising

INCOMINGTERMINAL

TURBULATOR

CIRCUITBREAKINGCHAMBER

NOPER AT NGSHAPE

3.-Small oil -volume, 33,000 -volt circuit -breaker,operated by compressed air.

OR V.A IRSUP,'"

VENT

OIL -LEVELINDICATOR.

SERIES AIR-BFIEAKSWITCH(ISOLATED POSITION)

FIXEDCONTACT

MOVING -CONTACTMEMBER

PORCELAININSULATOR

BAKELISEOPAPERTUBE

SERIES AIR -BREAK SWITCH OUTGOING(CLOSED POSITION) TERMINAL

SJ

INTAKE FROMAIR -RESERVOIR

Fig. 4.-Perspeaive view (part sectional) of a 132,000 -volt circuit -breakerunit, with small oil -volume switch, operated by compressed air.

from the oil -quenched arc, andit meant also that phase -to -phase faults became almostnegligible. It made thegeneral design of switchgearvery much more simple andcompact, and helped, too, inthe protective gear schemes,as it made earth faults almostthe only type of failure to beguarded against. A typicalmetal -clad switch in whichthere is no bare connection isshown in Fig. I. Here thewhole assembly can be dividedinto two parts, fixed and mov-ing. The two sets of altern-ative busbars are shown at C;and the device seen above theswitch itself at J allows theincoming cable to be connectedto either. Projecting from thebusbars and from the cable arespouts, and the switch assemblyitself can be pushed in, as itis shown in the illustration, sothat contact is made with thesespouts, or it can be completelywithdrawn to the right of the

figure by means of the rack and pinion gearat L, leaving the spouts covered by automaticshutters D, to ensure complete isolation ofthe outgoing circuit from the busbars. Theactual contacts are shown at A, one of themhaving its explosion pot removed for thepurposes of illustration. The incoming cableconnections are indicated by letter F, whileE denotes the current transformer, and G thevoltage transfOrmer, for protective gear andmetering purposes. The switch is closed bythe solenoid K through the linkage B.

By about 1930, switchgear manufacturerswere able to produce circuit breakers whichwould control circuits of up to 66,000 volts,and for normal carrying currents of as muchas 2,000 amperes. But there were still manyempirical factors used in their designs, andit was decided to organise laboratories on alarge scale for common use where sufficientpower could be available to test all typesof switchgear, if necessary to destruction.Special motor -driven alternators, with alarge fly -wheel to store energy, were usedin this woLk, and scientists began to learnmore about the fundamental principles ofarc control.

Before long all leading manufacturersbegan to develop forms of " explosion pot,"

96 NEWNES PRACTICAL MECHANICS December, 1944

Fig. 5.-Air-blast circuit breaker for 33,090 -volt circuits.

which were used to surround the fixed con-tact on the switch and to guide the arcthrough various forms of pasSage, whichhave the effect of driving the oil across orthrough the arc path, thus obtaining instantextinction at the first current zero in thealternating current wave.

With the help of these devices, our leadingdesigners were able to predict very closelythe performance of their switchgear underthe most severe conditions of short-cirCuit,and they were able, in many cases, to reducethe volume of oil considerably. The influenceof the design of explosion pot, the strengthof the spring, and other mechanical featureswere, at the short-circuit testing stations,capable of being observed with the greatestexactitude.

The cathode-ray oscillograph is widelyused in this work, since by its aid theexact voltage and current and time condi-tions in connection with the moment whenthe circuit commences to be interrupted canhe not only observed but photOgraphed forpermanent record. In modern installationsof switchgear of the general design's Hitt's:trated, there are both indoor and outdoortypes. In an indoor installation, the switcheswill be either self-contained, that is, of themetal -clad type as in Fig. t, or of thesame layout as regards the circuit breaker,but with the busbars and other gear en -closedin stone cubicles. The switch will beclosed, remotely, by means of a poWerfulsolenoid or motor -wound spring, and it will,of course, be tripped by a similar but smallersolenoid. The contact mechanism, as shownin Fig. 2, will consist of some form ofexplosion pot which controls the arc socompletely that, Olth the extremely rapidbreak, it is possible for a very small quantityof oil to be suflicient. Indoor inkallatiofisof this type are generally within the limit's Of

6,600 to 33,00o volts,although higher voltagedesigns are occasionallyto be found, Outdoorschemes will have asimilar switch, but inthis case the whole switchtank will be weather-prbof, and the connec-tions will be brought outthrough the too platein porcelain insulators .tobare connections, , fromwhence they are run to theoverhead busbars. Triereis no limit to the voltagefor which these schemesmay be designed. In thiscountry, there arc a vastnumber of 132,000 -voltc i r c ti i t breakers con-structed according to thisplan, while on the con-tinent And in Americainstallations up to 28okV have been success-fully commissioned.

Pneumatic OperationBut new lines of

thought about circuitbreaker design havegradually been winningtheir way to the fore.The simple oil - filleddesign, however carefullythe arc is controlled, can-not but require sufficientoil to constitute a seriousfire risk, and the " smalloil volume " types whichhave been manufacturedof late years, have beenbased broadly on thePrinciple of not onlyusing the maximum

control of the actual arc, but of pro-ducing an acceleration for the breakingmovement of the contact, of a greatlyincreased order. To do this, it has beennecessary to abandon the orthodox spring -and -linkage methods of operation and tosubstitute pneutatic methods where highpressure of compressed air, operated throughcarefully designed blast valves, acts on amoving piston or vane of the lightest possibledesign. This type of mechanism most con-veniently produces a short break whichwould not be sufficient for complete isolationof the circuit under all conditions, and soa second break which does not actuallyrupture fault currents-that is, it operateswhen the main circuit breaker has brokenthe circuit-is sometimes introduced.

This type of switchgear, which is uncon-ventional when judged by the standardshitherto existing, is illustrated in Figs. 3and 4. The first illustration shows a 33,000-volt installation where the orsecondary break is not required. Thecurrent enters at the extreme top and passesthrough the cireuif-breaking element, whichis the higher of the two porcelains on eachOf the three singleithase units, and leaves atthe bottom of the Switch. The air operat-ing mechanism is in the compartment on theleft, and the "storage cylinder for reserve airpressure is seen below. Fig. 4 is a dia-grammatic view of a 132,000 -volt circuitbreaker which has been in service for *SOinetime on the National Grid. The mainbreak, in the topmost vertical porcelain in-sulator, needs only 3o gallons of oil perphase, as c61mgared With the 1,300 or sogallons used on the more conventional,earlier types. Here the series air break isused, since the_shoft main break is not con-sidered sufficierii isolation .(mder Fall condi-tions. There are two air-Mtors, of the

vane type, one for the circuit breaker itself,

and one for the series air break.

Air -blast DesignWorking parallel with these developments,

other designers on the continent,' in Americaand in this country were endeavouring toobviate the use of oil entirely, by " blowingout " the arc by means of a powerful blastof air. There were many difficulties in thedevelopment of this design-for instance, itwas obviously absolutely necessary to extin-guish the arc at the first current zero afterthe contacts had parted, as if this had notoccurred the initial force of the air -blastwould have been expended, and there wouldbe no means of further arc extinction. Theseproblems have been satisfactorily solved, andit can be prophesied with some confidencethat future switchgear will be mainly of theair -blast design. Fig. 5 shows a typicalscheme for a 33 kV circuit. This incor-porates the auxiliary break mentioned abovein connection with the pneumatically -oper-ated gear, but this time it fulfils a differentand more vital function. The energising ofthe trip coil opens the main blast valve whichallows the air under pressure to flow up the .

blast pipe nozzles, and when it reaches themain contacts, which are kept closed bymeans of springs, it opens them in pistonfashion, and thus interrupts the circuitwhile in its subsequent rush to the exhaustvents it carries with it the ionised particleswhich form the arc. But the main contactsonly stay open as long as the blast is on,and so immediately after they have openedthe air pressure is fed into a simple pistonwhich operates the auxiliary or series break.The blast having been expended, the maincontacts drop back, but the circuit has beencompletely isolated by the opening of theseries break. For the closing operation theseries break alone is used. In some casesa resistance is automatically introducedmomentarily into the circuit during theopening stroke, and in the illustration this isshown mounted above the main contacts.The circuit breaker itself is that portion of

Fig. 6.-Air-break switch for 66o volts,1,600 amps.

December, 1944

the gear mounted immediately above thestepped bakelised-paper supports.

Low Voltage Circuit BreakersSo far we have considered entirely high

voltage switchgear for the standard 3 -phase50 -cycle systems. In the early days aswitch, whether for high or loN9 voltage, wasconstructed on much the same principles.But with the extreme specialisation that hastaken place in the various branches of theart of switchgear design, the low voltagebreakers which are equally important in thegeneral layout of the electrical industry,have developed along different lines. Fordirect current, the usual method of arc con-trol is to use a magnetic blow-out wherebythe connections to the switch come througha coil so disposed as to develop a strongmagnetic field which, when it interacts with

NEWNES PRACTICAL MECHANICS

the arc, causes it to be drawn into a conveni-ent and safe arc-shute which allows it .topass harmlessly into the air. The generaltrend of design both for D.C. and 3 -phaseA.C. circuit breakers for voltages up to,say, 600 volts, has been to increase the speedof operation by means of powerful springlinkage mechanisms, in which every possibledevice has been employed to reduce frictionand to do away with the effects ofinertia. A modern example, for 66o volts,1,600 amps, 3 -phase A.C. is shown in Fig.6. Special types of low voltage gear havebeen developed to meet every need. Radioengineers have, needed switches where thehigh frequencies of the currents they carryhave necessitated every insulating part beingof the special low -loss dielectrics which thewireless technician has found necessary.Mining engineers have required switches

97

which will pass the Government testingstation examination in respect of being flame-proof, and many ingenious devices are usedto ensure that no matter how severe thearc it cannot cause ignition of any inflam-mable gases in its vicinity.

This brief review of switchgear develop-ment shows that what was once a relativelyunimportant and certainly very simple partof the electrical engineer's equipment hasbecome the subject of a major branch ofelectrical science. The early pioneers couldscarcely have conceived, when they addedsmall improvements to the knife switch, ofthe colossal amount of power which laterswitches would be called on to control.

The author is indebted to Messrs. TheEnglish Electric Co. for permission to repro-duce Figs. t, 2, 5 and 6, and to Messrs. A.Reyrolle and Co. for Figs. 3 and 4-

Modifying Car Dynamos and Starters -3Rewinding of Armatures and Field Coils

IN part 2 of this series, a method was givenfor approximating the wire gauge sizeto use for the new winding, and the

importance of an accurate armature wind-ing diagram was emphasised. The mainessential of such a diagram is that it mustportray correctly the relative positions of thecoil sides, slots, commutator bars, and coil -to -bar connections, and to avoid mistakes, itshould be as simple as possible. Since thecoils of an armature winding are invariablyidentical, and as their connections followone another progressively round the arma-ture, there is nothing to be gained by show-ing all the coils on a winding diagram, sothat some simple convention, as shown inFig. 9, will be quite satisfactory ; withiPthismethod the winding is assumed to be openedout and laid flat. Fig 9a represents a " lap "winding, the coil ends being connected totwo adjacent commutator bars. The " span "of the coil is slot 1 to slot so and the fact thatthe mica between bar i and bar 2 fallsopposite slot 5 is recorded, since it fixes thecorrect position for the coil -to -bar connec-tion. The other type of winding used is the" wave " winding, and is depicted in Fig. 9b.The same general procedure is followed forfixing relative positions, but it will be ob-served that the principal feature of thiswinding is that the two connections to thecommutator now lie very far apart ; it isthus doubly important 'here to number thecommutator bars correctly. In the case ofmultiple coils, that is, where two or morecoils lie in the same slots, the connectiondiagram should be suitably modified, asshown in Fig. 9c.

Insulating the CoreHaving stripped the original winding, the

core can now be prepared for its new wind-ing and, as the old insulation will have beenremoved, the reinsulating process should betackled first.. In this important matter,cleanliness is most essential, as many break-downs have been caused through metal filings,swarf, and dust, all of which are usuallygenerously scattered around the amateurworkshop. The reader should, when insu-lating % core, endeavour to adequately coverall metal likely to come in contact with thecoils, and various insulating materials areused in this connection. The ends of thecore are usually protected by fibre washers,whilst " Empire " cloth or thin leatheroid isuseful for the slot portion ; with regard tothese slot linings, they should be made largeenough to extend some way out of the slotso that, after winding, they can be turnedover and wedged in place, as shown in Fig.

By D. E. BARBER

(Continued from page 54, November issue)so. In the case of hand windings, wherethe slot lining provides insulation as wellas mechanical protection of the coil, a thick-ness of .005 inch " Empire " cloth, plus alayer of .or inch leatheroid, will providesufficient insulation for voltages up to 250.

Hand. WindingsThe majority of automobile dynamo wind-

ings are hand windings, that is to say, thatthe coils are wound on to the, core straight off

ICA

.7 I\ 1 \Bar 1 I Bar Bar, Bar5. Bar&I .

AMca opposite Mica cIppositeslot .5 sib t 1.

(a) (b)

. IMica opposite slot I.

(C1Fig. 9.-Winding diagrams

the wire drum. As in all types of armaturewinding, hand winding calls for a fairamount of skill and practice, and the aimof the beginner should be to take great painsrather than to rush the job. After insulatingthe core, the armature should be placedbetween the centres of a lathe or in a suit-able wooden frame, and the coils should bewound on, care being taken to avoid kinks

in the wire. The starting end of the wireshould be plainly marked, preferably withcoloured cotton sleeving and, after every fewturns, the windings should be gently tappedwith a hide mallet or fibre block so that itbeds down nicely into position, thus avoid-ing bulges. When the reader becomes ex-perienced, it will be found that the wires canbe coaxed into place without a great dealof tapping, and in this way the danger ofshorted turns is appreciably reduced. As eachcoil is completed, the finishing end shouldbe marked with a second piece of sleeving, ofdifferent colour, and secured before proceed-ing with the next coil. With mulitple coils,after putting on the required number ofturns, the wire should not be cut, but shouldbe looped and twisted, thus forming a tappingon the coil these tappings should also be

imarked with some distinctive colouring.After the loop has been brought out, theremaining turns can be put on to the coil.To avoid short circuits between coils, smallpieces of good quality brown paper shouldbe placed in position wherever the end -windings cross each other, as these are inher-ently weak points. Similarly, a strip of thesame material can, with advantage, be placedbetween the top and bottom coil sides in theslots.

Former WindingsOccasionally it may become necessary to

rewind an armature, using the former wind-ing method, which means that the indi-vidual coils are wound, formed into shape,and insulated before assembling into posi-tion on the core. Fig. t s shows the type ofwooden frame or former which is used towind the coils, together with the method ofwinding and tying off the coil ready forremoving from the former. Fig. s lc is asketch of a completed former -wound, multiplecoil, showing particularly the " step " whichshould be given to it in order that it maybe assembled neatly into position on the core.The taping up of the coil should, for wind-ings up to, say, 250 volts, consist of one half -lapped layer of .005 " Empire " tape, inwhich case only the leatheroid slot liningneed be included, as this serves as mechanicalprotection.

When the core is provided with semi -closedslots, former winding is thereby complicatedas only the end windings can be taped up,since the slot portion of the winding mustbe left free, in order that the individual con-ductors may be passed into the lot a few ata time. In this case the slot insulation shouldbe the same as would be used for the equiva-lent hand winding.

98 NEWNES PRACTICAL MECHANICSLining turnedover after

winding

(a) open type slot

Lining reedy foe Lining turners overinsertion of and wedged <site,

winding winding

(b) Semi -closed type slotFig. ro.-Slot

Connecting -up and Finishing -offAfter the coils have been assembled on the

core, the connections to the commutator canbe made. Except in the case of very fineconductors, the commutator bar should beprovided with a small sawcut to take the twoconductor ends, which will be soldered to it.Before actually connecting, the space behindthe commutator should be built up withstring or tape to give good support to thewire ends. When soldering, only goodquality resin flux should be used, and careshould be taken that the solder runs rightinto the sawcut mentioned above. A com-mon mistake is to use an iron of insufficientsize, so that the joint does not get hot enoughfor the solder to run properly. The leadsfrom the coil to the commutator bar shouldbe protected by sistoflex sleeving right up tothe actual connection, since it is often herethat shorts occur.

With regard to securing the coils in theslots, if semi -closed slots are used the insu-lating lining can be turned over and a wedgeof fibre or bakelite will then hold the coilsin place. In the case of open slots, how-ever, the lining should be turned over asbefore, but some turns of binding wireshould be then wound tightly round thecore to secure the coils. Sections of thecore are provided with a reduced diameterto take these bands, thus preventing themfrom standing above the surface of the restof the core. Examination of the originalarmature before stripping will make clearthe method to be followed. In addition, aband is usually wound over the front andback end -windings, but these are often ofthin, strong twine, whereas the core bandsshould be of copper wire, about No. 24gauge, and tinned to facilitate sweating upin several places to secure them. The finalstage is the dipping of the armature in somegood quality varnish to keep out the damp ;if the wire used in the coils is enamelcovered, the armature should not be dipped,as some varnishes- attack the enamel cover-ing. An external coat of shellac or similarvarnish is, however, quite permissible. Ifconsidered necessary, the commutator cannow be skimmed up in a lathe, using a veryfine cut and a rather high speed ; careshould be taken that the soldered connectionsare not ripped off during this operation.

Field CoilsThe armature winding having been suit-

ably dealt with, attention can now be turnedto the field coils. The preliminary tests, asoutlined in article 2 of this series, will haveestablished the number of ampere -turns thatthe new coils must provide. A method isnow required for deciding what size of wireto use and how many turns to wind on. In

the case of series coils, the calculation issimple, as the field current is the same as thearmature current, so that in order to findthe number of turns to put on, divide therequired amp -turns by the field current.The size of wire depends on this currentand can be found by assuming that a " cur-rent density " of about 2,500 amps per squaeinch of copper section is permissible, so thatif the field current were, say, to amps, thewire would have- to have a sectional area of.004 square inches. On looking up the wiretables it will be found that No. 15 S.W.G.has a section of .004072, and would thus besuitable.

The design of shunt coils is a little moreinvolved, as the wire size will depend on thevoltage at which it is desired to work thefield. Usually, to allow for a little variationand the inclusion of a small series resistancefor adjustment, the voltage across the field istaken as about 75 per cent. of the terminalvoltage. Before the calculation can be made,an estimate of the average length of one

Armature

(a)

(b)

Supply'

(e)

Fig. 12.-Diagrams illustrating methods ofconnecting.

turn of the original field coil should be made ;the following formula will then give the" ohms per yard " value for the wire sizerequired. Reference to the wire tables willthen enable the equivalent S.W.G. to beread off.

Terminal volts x 36 x 0.75Amp -turns Av. lgth. of Number ofper coil x one turn x coils inrequired in inches seriesTo return to the

example of designgiven in article 2 ; itwill be recalled thatan excitation of 400amp -turns per coilwas decided upon,that the machine wasfour pole, and thatthe terminal voltagewas to be 520. Ameasurement of theoriginal field coilsshowed that thelength of an. averageturn was it.8inches, s o thatthese values

(a) (b) (C)Fig. i i.-Three stages in winding.

December, 1944

can be substituted in the formula as follows:120 X 36 X 0.75Ohms per yard = 400X ii.S x 4. --°189

From the wire tables, the nearest sizes areNo. 29 S.W.G. and No. 3o S.W.G. Either ofthese may be used, the former giving slightlymore ampere -turns, but, at the same time,increasing the field excitation loss a little.The whole of the available space should beutilised for the coils, so that after fixing thewire size, as many turns as possible shouldbe wound on. It is interesting to note thatfor a given gauge of wire the ampere -turnvalue of a shunt coil is almost independentof the. number of turns, although too fewturns will cause a high field current with acorresponding increase in excitation loss.

The actual winding of the field coilsshould present no special difficulty, and will -be found much simpler than the armaturewinding. The rule of cleanliness is equallyimportant in the case of field winding, andshould be rigidly adhered to. A coil wind-ing former of similar design to the armaturecoil former should be made, and the neces-sary turns can then be quickly wound on.Two layers of .005 inch " Empire " tape willprovide adequate insulation, whilst a furtherlayer of cotton tape may also be applied ifmechanical protection is desired ; the tapeshould not be drawn too tightly, otherwisedistortion of the coil will result. Coil leadsshould, if possible, be of a flexible nature, asbreakages of the wire often occur where thewires leave the coil. It will be found thatthe remarks previously made on the subjectof dipping armatures are also applicable t,ofield coil dipping, and in the majority of casesthe same varnish can be used for both jobs.

Compound Field WindingsFig. 125 and 1213 show diagrammatically

the method of connecting up the armatureand It'd system of a series and shunt machinerespectively. Sometimes, as was mentionedin an earlier article, it is desirable to boostup the field of a shunt machine when on loadby means of a few series turns ; this extraseries winding is called a compounding wind-ing, and is connected as shown in Fig. I2C.If, on running up for the first time, it isfound that the inclusion of the compoundingwinding reduces the terminal voltage onload, the winding is opposing the shuntwinding, and should be reversed. Thenumber of turns to put on such awinding is largely a matter for experimenton the basis of individual requirements.For instance, if the generator supplies a loadvia a long cable run, it is a good plan tomike the full load terminal voltage a littlehigher than the no-load voltage to compen-sate for the drop in voltage in the cable. Inthis case, " over compounding " can beadvantageously employed, this entailing a fey,series turns over and above the normalvalue.

(To be continued.)Thread to hold

coil together

.StstO flexsleeving

Tapping loop ,fatlyfor cutting

December, 1944- - NEWNES PRACTICAL MECHANICS 99

Rocket PropulsionFurther Details of American Research The FirstBritish Rocket Society By K. W. GATLAND

(Continued from page 5o, November issue)

SINCE its formation in 1930, the Amer-ican Interplanetary Society publisheda monthly Bulletin, but in May, 1932,

the title of this was changed to Astronautics-a journal to -day heralded as the finest ofits kind. From that time until January,1933, the Society's official publication con-tinued to appear each month, but in orderto reduce expenditure, issue has since beenmade at quarterly intervals. Economy thusachieved financially, a more elaborateresearch programme was drawn up, and inSeptember, 1933, the construction of threemore rockets was begun.

In the Spring of the year following, how-ever, the Society changed its name, the term" Interplanetary " being discarded in favour

Forwardlaunchingguides

Oxygenfeed lineand controlvalve

Fuel tank(Petro

Combustionchamber

Exhaustnozzles(Four)

Fuel feedline andcontrol valve

Jointing ring

Liquid oxygentank

pearfairing

Fig. r4.-Experimental rocket No. 4, of theAmerican Rocket Society (1934).

of the more conservative American RocketSociety, a change made in the belief thatmany prospective members considered theSociety's space -crossing ideal unattractiveat that early stage of technical development ;nevertheless, it was emphasised that thealteration by no means meant to infer ageneral abandonment of the interplanetaryidea.

A.R.S. Revised Research ProgrammeFor the prosecution of the new develop -

mutt programme, the A.R.S. ExperimentalCommittee was divided into three sections,and certain research engineers made respon-sible for the individual design and construc-tion of the three projected rockets, thefollowing, many now well known amongrocket 'authorities, being prominently fea-tured : Experimental Rocket No. 3, G. E.Pendray (at that time President of theSociety), A. Africano and B. Smith ;Experimental Rocket No. 4, L. Manning,C. Ahrens, A. Best and J. Shesta ; andExperimental Rocket No. 5, N. Carver,H. F. Pierce, and N. Schachner.A.R.S. Experimental Rocket No. 3-

DesignThe general layout of the Society's third

rocket (Fig. 13) was, to say the very least,original.

The combustion chamber was located atthe rocket " head," the top of which formedexternally a conical nosing. The motorwas built in two halves for easy replace-ment should any damage be sustained duringtesting runs.

A nozzle of high expansion ratio extendedthe entire length of the rocket, and foralmost half its depth the nozzle was jacketedby the petrol tank, which served as coolantfor the nozzle throat, the heat dissipationacting conversely to vaporise the fuel, andfacilitate the feed problem.

The liquid oxygen tank was positionedconcentrically within the outer rocket shell,and by this arrangement the volatile " sup-porting " element was adequately insulatedfrom combustion heat. The space betweenthe two tanks was employed for storage ofcompressed nitrogen, employed for feedingthe fuel.

Supported about the lower portion of therocket, a venturi duct, or " thrust augmen-ter,"-i device designed to increase thrustand provide stability during flight - wasfitted.A.R.S. Experimental Rocket No. 4-_

DesignRocket No. 4 (Fig. 14) differed consider-

ably from the former design ; the motor,located at the rocket " head," incorporatedfour nozzles inclined laterally to eject theexhaust away riom the narrow section tanks.The fuel tank was supported directly beneaththe motor, and the liquid oxygen tank belowthis.

The complete rocket, fitted with nose andtail fairings, measured 7ft. 6in., the maxi-mum cross-sectional diameter being only3ft.

A.R.S. Experimental Rocket No. 5In the fifth rocket project a feeding

system was evolved which dispensed entirelywith the compressed gas " charger" ; instead,

CombustiOnchamber

Oxygen feedline end valve -aky

Fuel tank(Petrol)

Supports -(lour)

Fuel, feedline 'end valve

Expens ionnoz z le

_Liquid oxygentank

Fig. 13.-Experimental rocket No. 3, of theAmerican Rocket Society (1934).

the expansion of the liquid oxygen beingemployed as the fuel pressure medium.This was arranged by the simple procedureof housing both liquids within a commoncylindrical tank, the two fluids being separ-ated by a movable piston. Pressure dueto expansion of the liquid oxygen causedthe piston to rise in the cylinder, so apply-ing pressure to the .fuel, the pressure withinthe oxygen compartment at the same timeremaining adequately sufficient to provideself -feed of the supporting " element. Thereaction motor was fitted, as in RocketNo. 3, at the head " of the projectile,serving the dual purpose of combustionchamber and nosing.A.R.S. Experimental Rocket No. 4-

TrialsThe first rocket to be completed, Experi-

mental Rocket No. 4, was put to preliminarystand test on June loth, 1934, the trial'taking place at the Society's proving ground,Staten Island, New York. As a result, afault was found to be that the inlet portsto the combustion chamber did not allowfor an adequate supply of fuel, which resultedin oxydation and " burn out " of the motor.

Another motor was constructed, and the

100 NEWNES PRACTICAL MECHANICS December, 1944

Professor Hermann Oberth and others of the Verin fur Raumschiffahrt E.V. In theforeground is one of the early " Mirak " type rockets. The other is an altitude rocket

developed by Oberth (1931).

necessary alterations to the feed systemcarried out, but it was not until Septem-ber 9th that the rocket was finally launchedin free -flight.

The test was reported in the October issueof Astronautics, describing the flight asfollows

" Directly the valves were opened, therocket leaped from the launching rack.Almost vertical flight was maintained fornearly 30o feet, at which point the rocketturned rather sharply out to sea. It wasat this point, observers assume, that theburned out nozzle failed, shifting thedirection of the propulsive forces actingon the rocket. The rocket rapidly sloppedover until it was headed directly towardsthe wafer. Shortly after the change ofdirection, it began to ' hunt.' It struckthe ocean with a terrific splash, the forceof the impact bending the upper part."During test, the rocket rose to a maximum

height of 382 feet, and attained a speed wellin excess of boo m.p.h.

The projectile was reco4ered and exam-ination of the motor revealed that one ofthe four nozzles had suffered severe burn-ing rear of the " throat " with the resultthat the reactive balance had become upset,thus affecting the rocket's stability. Dueto this defect, the parachute releas'e mechan-ism did not function.

The term " hunt " referred to in theofficial test report may require elaboration.This is merely an expression meant toconvey the manner in which a projectile maybe observed to deviate from side to side asthe result of compressibility, built up at thenose, when its forward speed is in the sonicregion. The swerving is a natural inclin-ation to dodge this local compression area.

This problem has since been overcome,to some extent, by the employment of auto-matic stabilising devices, such as the highlysuccessful gyro/vane system tested duringthe Goddard rocket trials of 1935.

In the light of experience gained fromthe tests of Experimental Rocket No. 4, theA.R.S. Experimental Committee concludedthat a great deal more routine ground testwork was necessary before any practical gaincould result from the firing of Rockets Nos.3 and 5.

As the rocket motor had been the chieffault in every experiment hitherto con-ducted,. the main effort was directed towardthe general improvement of the propulsionunit.Reaction Motor Tests

At the Society's proving grounds at Cres-wood, on April 2ist, seriesof individual motor tests was made, and anumber of motor forms embodying bothlong and short nozzles were put throughtheir paces on the proving stand. The resultsof various tests were, however, by no meansConclusive. It was found, for instance,that the length of the nozzle did not haveMaterial effect on the develdped thrust of agiven combustion chamber. Some measureof improvement was found when. varyingfeed pressures were tried ; it was discovered,for instance, that efficiency was greatest if

the fuel was introduced into the chamber ata high piasSicre.

The most satisfactory results of the day'swork were obtained during the second testconducted, When a maximum thrust of 591b.was recorded, the chamber pressure .being3cTolb. For this particular experiment, ashort nozzle was fitted. The maximumfiring period was 17 seconds.

As the result of these and subsequentmotor trials, a considerable amount ofempirical data has been obtained for theresearch files of the Society. Such is thereliability of this data that most featuresof performance can now be predeterminedduring design, the test results being mereconfirmation of the calculated figures. ThesemethOds of calculation will be discussed ina subsequent article.British Rocket Development -Limita-

tionsIn Britain, the development of the rocket

can hardly be said to have received encour-agement-officially, the use of liquid oxygenfor purposes of rocket experimentation isprohibited. The sole range of propellantavailable for research in this country mustcome within the bounds of the specifiedterm " approved companion " ; that is,certain fuels Of the solid " or powdervariety. Yet the restrictions do not endhere ; under the obsolete ExplosiVes Act,1875, any experimental rocket, if the experi-menter wishes to " keep within the law,"thoUgh it employs as fuel " approved com-position," may be put to test only if thefollowing conditions are satisfied: (a) Thefiring range mast be sanctioned by the localpolice authorities concerned. (b) Thedesign of the rocket must be approved bythe Secretary of State, through his advisers,and (c) The filling of the rocket most takeplace in premises licensed under the Explo-sives Act, 1875. It is stated that approvalcould not, under any circumstances, be givenfor the use of the liquid oxygen -hydrocar-bon propellant ; small wonder that to -day,apart from the developmenTi of our Americanassociates, we find the enemy alone usingtechnically progressive rocket weapons.The First British Rocket Society

Despite the fact that almost insurmount-able difficulties lay in the path of the would-be British rocket experimenter, thanks tothe determination of one, P. E. Cleator

Valier rocket car, powered by the Heylandt constant volume combustion motor, being chargedwith liquid oxygen prior to a test (1930).

December, 1944 NEWNES PRACTICAL MECHANICS 101

(author of a foremost rocket literature inthe English language, " Rockets ThroughSpace," pp. 246, Allen and Unwin, 1936),the first and probably still the most re-nowned rocket organisation yet formed inthis country, the British InterplanetarySociety, was brought into being in 1933.As a beginning, important Press contactswere made, and thanks to resultant publicity,interest in the new science of astronauticswas slowly but surely aroused all over thecountry.

The first official meeting of the Societytook place on October 13th, 1933. Thefounder, P. E. Cleator, was unanimouslyacclaimed president, while C. H. L. Askhambecame vice-president, and L. J. Johnson,secretary. The number of persons in attend-ance at this intial assembly of the Societywas six. By the end of the year the mem-bership figure has risen to 15, and dueto added. publicity provided by the firstissue of a Society Journal, which for somemonths was reflected in the National Press,the Spring of 1934 found the Society'snumerical strength at 29.

The group's chief problem at that earlystage was one of limited finance-publicationof a Journal at regular intervals washardly possible on the subscriptions of sofew, leave alone to allow for practicalresearch. Various avenues were exhaus-tively explored in the attempt to gainfinancial support, but with no success.Finally, in desperation, the Government wasapproached, and this is what P. E. Cleatorhas to say of the move in his book," Rockets Through Space ": " . . . The AirMinistry evinced not the slightest interest.The Under -Secretary of State, in refusing

to discuss the matter, explained that althoughrocket experimentation abroad was watchedwith interest, scientific investigation into itspossibilities have given no indication thatjet -propulsion could be a serious competitorto the internal-combustion engine and thepropeller of the aeroplane. In the circum-stances, there could be no justification forspending either time or money on rocket

9experimentation. . .

Here is a classic example of the handicapswhich oppose progressive thought in thiscountry. To -day, we can judge for our-selves how wise was that official decision ;the German Messerschmitt Me. 163 rocket -propelled fighter, and thermal -jet aircraft,bears adequate testimony.

Further Goddard ResearchSoon after the Guggenheim grant made in

1929, Dr. R. H. Goddard set up an isolatedlaboratory near Roswell, New Mexico, andthere continued with his experimentalresearch.

Work at Roswell consisted largely ofroutine tests of rocket motors and feedingsystems, and apart from a brief report, whichappeared in the American Rocket SocietyJournal, Astronautics, September, 1934, littleinformation of Goddard developments wasforthcoming :

" The work consisted in the constructionand flights of a number of models designedprimarily to test operation rather thanreach great heights. Flight speeds in excessof 400 m.p.h. were obtained. . . ."

In March, 1935, however, informationwas given of the free -flight trial of4a largemeteorological rocket, which incorporated aunique stabilising device.

During an initial trial on May 31st, therocket rose to an altitude of 7,50o feet,attaining a velocity in excess of 700 m.p.h.,the time taken in reaching the peak oftrajectory being 14.5 seconds. The gyro -stabilising system embodied was designedto operate when the rocket axis deviatedmore than to degrees froth the vertical, andat this angle the controlling mechanismbrought into play vanes which acted todeflect the rocket exhaust, and so momen-tarily offset the thrust reaction, to returnthe projectile to its true flight path.

A motion film taken of the ascent showsthe rocket shooting upwards, the action of thestabliser being clearly marked by the un-dulation of the projectile as it is constantlycorrected to the vertical. Further tests ofthe gyro -controlled projectile took place inOctober of the same year. The heightreached on this occasion was 4,000 feet.

The rockets tested in 1935 weighed from58 to 851b. No particular attention wasgiven to obtaining lightness of construction.

Goddard Motor Trial ResultsDuring the test of a certain liquid oxygen/

petrol fuelled reaction motor, weighing51b., the combustion chamber eing 5.75in.internal diameter, a maximum thrust of2891b., and an efflux velocity of 5,000feet per second, were recorded. The motordeveloped 1,030 h.p.

A report of Dr. Goddard's research pro-gress, principally conderning the Roswellexperiments, was published in 1936 underthe "title Liquid Propellant Rocket Develop-ment, ropp., Smithsonian Misc. Collections3381.

(To be continued.)

Letters from ReadersEngineer -built Houses

SIR,-I have read with great interest yourseries of articles on engineer -built

houses, and I am very glad to know thatengineers are at last going to interest them-selves in the building of houses.

' After the last war the engineers tackledthe motor -car and not only greatly reducedthe cost of cars but also improved both theirperformance and looks, and I hope they willdo the same for houses.

I have noticed that when unloading bricksfor house building they are taken five at atime and thrown from hand to hand, andhave often wondered why bricks are notmade five times as large as they are now.If they were it would surely save cost inbuilding.

Also, why take, say, a door in plain woodand hang it and then paint it with a brushunder the worst possible conditions. Surelyit would be better to spray -paint it in afactory and take it to the site ready forhanging.

The bombings we have endured have, Ifeel sure, sickened a lot of people of the verythought of plaster ceilings, and also of plasteron walls, and I hope we shall see plasticboards in place of plaster.

There are many things in the houses wehave had to live in that can be improvedand money saved by alternatives, and I, forone, am very glad to see that at long lastsome brains and new ideas are to be intro-duced into the building trades.

A. H. BENTLEY (Horsham).Power for TractionSIR,-I would like to point out an error

made in reply to a reader's query,which appeared in your issue of PRACTICALMECHANICS dated November, 1944.

Your correspondent states that the resistanceto the motion of a pneumatic-tyred vehicleon normal road surfaces is the sum of :

(a) Total weight (1b.)- divided by 20.(b) Total weight (lb.) divided by the

gradient factor.(c) Frontal area (sq. ft.) multiplied by

(ft. per

25

(d) Total weight (lb.) multiplied by acce)-eration in ft. per sec. and divididby 32.2.

The force required to accelerate the car,however, is not given correctly by (d), as noallowance is made for the acceleration of the

BOORS FOR ENGINEERSGears and Gear Cutting, 6/-, by post 6/6.Workshop Calculations, Tables and For-

mulse, 6/-, by post 616.Engineers' Manual. 10/6, by post 11/..Practical Motorists' Encyclopmdia, 1016, by

post 11/-.Motor Car Principles and Practice, 6/-, by

post 616.Wire and Wire Gauges (Vest Pocket Book),

316, by post 3/9.Diesel Vehicles Operation, Maintenance

and Repair. 61-, by post 6/6.Watches : Adjustment and Repair, 6J-, by

post 6/6.Plant Engineer's Pocket Book, 6/-, by post

6/6.Screw Thread Manual, 6/-, by post 6/6.Mathematical Tables and Formula; (Vest

Pocket Book), 3/6, by post 319.Dictionary of Metals and AllOys, 10/6, by

post 11/,Published by

GEORGE NEWNES, LTD., TOWER HOUSE,SOUTHAMPTON STREET, LONDON, W.C.2

engine parts, road wheels, and the whole of thetransmission system.

The force required to accelerate the abovementioned masses is given by :

IA+ G2IB x fF

where F -Force (lb.), r --effective radius ofroad wheels (ft.), f =acceleration, g=--32.2,IA =moment of inertia of road wheels andtransmission system (lb. - ft.2), G= gear ratio. -

Speed of engine (r.p.m.)- Speed of wheels (r.p.m.' 1B =moment of

inertia of engine parts (lb. -ft.2).This force F should be added to (a), (b),

(c) and (d) when calculating the requiredtractive effort.-F. L. ELLis, G.I.Mech.E. (Oxford).

" Catalin "SIR,-We have noticed in your November

issue of PRACTICAL MECHANICS that acorrespondent has inquired about informa-tion concerning the material `" Catalin," andthat you have stated that " Catalin " is aproprietary product manufactured andmarketed by the Catalin Corporation ofAmerica.

We would advise you that " Catalin " hasbeen manufactured and marketed in GreatBritain by this Company since 1937. It isa proprietary product and, as you say, ismanufactured by the controlled chemicalinteraction of Phenol (carbolic acid) andFormaldehyde (formalin). The material isthen cast into sheets, rods, tubes, etc., forspecial castings of particular designs." Catalin," as distinct from mouldings (i.e.,Bakelite), is produced with or without afiller to make transparent, translucent oropaque objects by a casting process.-CATALIN LIMITED (Waltham Abbey).

102 NEWNES PRACTICAL MECHANICS December, 1944

in order to speed up changing of the sets,and the accommodation of the travellingplayers consists of fully equipped dressing

THE WORLD OF MODELSBy "MOTILUS"

This Month We Present "Drama in Miniature"-a Consulting Engineer's Model Theatre; AlsoMore Post-war Model Planning, and the Ubiquitous "Christmas Gift"

THIS war has at long last brought thetheatre to , the people. E.N.S.A.,C.E.M.A., and other organisations

have carried the drama of to -day to muni-tion works, canteens, large army camps, andeven to small isolated posts in all parts ofthe British Isles and to our armies overseas.

Most of the companies travel completewith their scenery and props of a standardsize suitable for a small stage or platform,sometimes slaying three or four days, some-times only one night and then moving on.There is usually a general manager and astage manager responsible for the production,and a selection of professional players.

When one pauses to consider that there

Mr. .7. Cameron Ridley, the designer of the travelling theatre, with his model.

is only one town in fifty in this country thatpossesses its own theatre, this new regimeof E.N.S.A. and C.E.M.A. has given thosein the Forces particularly, and of coursemany civilians, hitherto unsuspected oppor-tunities of seeing much that is good of Eng-lish drama from Shakespeare up to Shaw,Priestley, and Coward.

Model Traveling TheatreIt has however fallen to the lot of a Mid-

land consulting engineer, Mr. J. CameronRidley, to design and make a model of whathe considers the ideal travelling theatre.One essential for a successful performanceto be given is the atmosphere of " theatre."Mr. Ridley has designed a semi -permanentstructure of timber, which incorporatesmodern lighting, comfortable seating, goodaccoustics and ventilation, and an unim-peded view from all angles, of the stage.The main building can be adjusted in sizeto accommodate audiences small and large,and with the skill of the travelling show-men, the theatre can be erected in a fewhours.

The essential features comprise the pro-perly raked floor and the usual " tip -up "theatre- seats. There is a revolving stage

rooms and living quarters, among which areincluded dining room, bedroom, bathroom,and kitchen.

Being complete and self-contained, thistheatre would have the great advantage of

accommodating its artists, thus overcomingthe trouble of securing local temporary" digs."

The structure of the auditorium erected.Mr. Rialey's plans and models have been

examined by theatre experts, and manythink that a travelling theatre as depictedin these illustrations could easily become,under efficient management, an economicand practical proposition, with toursarranged in the same way as obtains withthe existing theatre. There would be theagent preceding the " tour," who would goin advance arranging publicity, settling thesite and dealing with the bookings. Theparts of the structure would be conveyedby lorries with a team of erectors to setit up and equip the interior. These menwould be responsible for back -stage andfront of the house labour during the shows.

Mr. Ridley has prepared a memorandumon his Travelling Theatre, for which heestimates a capital outlay of just over

rz,000 would cover the theatre and itsequipment without the show.

The stage as viewed from the audience.

December, 1944

The photographs show various stages inthe erection of the model, which is to ascale of in. to the foot, or 1/48th actual size,The dimensions of the model building are3oin. by t4in., representing an actual size of125ft. by 55ft., a space which it is not diffi-cult to find in or near most towns orvillages of any size.

For years, says a writer, the travellingcircus has made merry with the millions.Here is a chance for the theatre to take thesame road. Any reader interested in thetravelling theatre will do well to get intouch with the inventor and designer, Mr.J. Cameron Ridley, with a view to its adop-tion and a welcome extension to the" Theatre to the People movement.

NEWNES PRACTICAL MECHANICS

Photographic copy of coloured drawing of one of the Sharp Roberts engines built for theSouth Eastern Railway in 1844.3

A Waterfront ModelAs another example of post-war model-

ling I am pleased to he able to publisha picture of the scheme put before thePeterborough City Council by the CityEngineer of Peterborough, Mr. F. I. Smith,A.M.I.C.E., showing a proposed layout ofthe almost waste !and in between the riverNen and the open-air swimming baths.This consists of the conversion of the almostwaste land near the river front into aflowered and treed walk, and the erectionof a boat -house and café, the constructionof an artificial boating lake, and other amen-ities of a city park.

It is honed to put this in hand as soonas hostilities cease, when work will berequired to eliminate the unemployment" gap " which appeared after the last war.Centenary Exhibit!on

Many railway fan readers will no doubthave heard something of theexhibition organised by t h eSouthern Railway to celebratethe centenary of the opening ofthe South Eastern Railway atMaidstone, in September, 1844.The exhibition was held at themuseum at Maidstone, and con-sisted of about eighty old prints,photographs, models and news-paper cuttings. The Mayor ofMaidstone (Alderman Sir GarrardTyrwhitt-Drake) on .opening theexhibition said he recalled thedays when the railway w a sfacetiously called the "LondonSmashem and Turnover Rail-way." In .those days the train left Maidstone at to in the morn-ing and arrived in London underthe hour, which is bet thanthe timing to -day.

Among the . e0ibits in theSpecial glass case were a modelof a " Schools " class locomotive,a " Merchant Navy " class loco-

motive, and also a model of the new " Q. t."class " Austerity locomotive. There wasa very fine large coloured drawing of oneof the Sharp Roberts engines built for theSouth Eastern Railway in 1844, which isreproduced on this page. Had it beenpeacetime when this exhibition was held,there is no doubt it would have been muchMore fully attended by a number of visitorsoutside the Maidstone area. An interestingbrochure was published, which gives par-ticulars of the early days of the railway andits incorporation in the Southern railwaysystem on the electrification of the lineopened on July 2nd, 1939.

The Model Hobbyist of the Future ?This issue reminds us that Christmas is

rapidly approaching again-the sixth wartime Christmas. I wonder what some ofour ten -Year -olds of to -day would think if

A young model locomotive owner, piecing together his woodenconstructional model of a locomotive.

103

A good exanzple- of post-war modelling.

they could go round the toyshops of Londonas they were in December, 1938, wheneverything was to be had for the asking ?Complete clockwork train sets for abouthalf a crown, ingenious mechanical noveltiesof all kinds from 6d. upwards, Bassett-Lowkeand Hornby and American and Germanmade clockwork and electric trains of allprices. The present generation have cer-tainly had to be satisfied with much simplertoys owing to wartime conditions-in manycases rather crude ones. This will be a helpto those manufacturers who have had toturn over during the war to Governmentwork, and will not be able in the first yearof peace to produce the marvellous range ofnovelties that we were able to feast our eyeson as late as Christmas, 1940.

Will the modern boy still like the rail-way and the ship, or will his mind be takenup with tanks, aeroplanes and other weaponsof war of which he has seen and heard somuch during his impressionable years.

Some boys have been lucky enough to getwooden toys made by craftsmen in theirspare time, and the young lad in this pictureis spending a happy Christmas holiday withhis wooden constructional engine. Whynot try your hand at this sort of thing ? Itis simpler than it appears.

Safety Device for Electric IronsTHAT handy domestic appliance, the elec-

tric iron, when left unattended withcurrent passing through it, ifbrought in contact with in-flammable material, wouldconstitute a danger. ' To protectagainst this contingency, an in-ventor has devised simple andeffective means for visuallyindicating the passage of currentthrough the heating element.

His device comprises a handle,of which a part or the whole isformed from transparent ortranslucent material. In thishandle there is a recess for theaccommodation of an electriclamp which, being wired in thecircuit of the heating elements,when the current passes through,illuminates the handle. Not onlydoes this arrangement act as areminder to the operator, but italso affords to other persons aclear warning of the state of theappliance. The device may alsobe utilised in connection witha soldering iron.

104

QUERIES ci,vtd

ENQUIRIESA stamped addressed envelope, three pennystamps, and the query coupon from the currentissue, which appears on back of cover, must beenclosed with every letter containing a query.Every query and drawing which is sent mustbear the name and address of the reader.Send your queries to the Editor, PRACTICALMECHANICS, Geo. Newnes, Ltd., Tower House,

Southampton Street, Strand, London, W.C.2.

Artificial SnowT WISH to construct what IS, I believe, called a

" Snowstorm." It consists of a hollow glasssphere of approximately 3in.diameter, containinga model building and some small white flakes.The latter, when the sphere is shaken, swirlaround and gradually settle, giving the impressionof falling snow. For the snow I have tried thefrost used for sprinkling on Christmas trees, butit sinks too rapidly, even when the sphere has beenfilled with water. Could you please suggest aliquid, clear, chemically inactive, and with aspecific gravity slightly higher than that of waterfor use with this "frost," or alternatively, asuitable material for the " snow " ?-E. Philbin(Hove).AN excellent material for the " snow " to which you" refer, is pure benzoic r acid, which is a light,crystalline material. Alternatively, you could use purenaphthalene flakes, but benzoic acid is better. Eitherof these materials can be obtained through a localdruggist. There is no heavier liquid than water whichwould be suitable for your purpose, unless, perhaps, youused a strong solution of glycerine (if you can obtainit I). A strong solution of sodium silicate (waterglass)might suffice for a time, but it would tend to go cloudy.

Anodic Treatment of AluminiumCAN you give me particulars of the process for

the anodic treatment of aluminium and lightalloy parts ? What current density per squareinch of metal to be treated is considered best ?Assuming that low voltage D.C. current is avail-able, together with simple home-made electro-plating baths, is it considered that the processcould, successfully be carried out in a modelengineer's workshop ?-G. W. Plumbe (Wick).THE anodic treatment of aluminium and light

alloys is an electro-chemical process in whichthe parts to be immunised against corrosion are madethe anode in an electrolyte solution, e.g., a 3 per cent,solution of chromic acid (CrO?) in water at 40 deg. C.The current consumption is approximately 0.2 kW.per sq. ft.!of surface treated. Other electrolyte solutionsare oxalic acid plus chromium salts, or dilute sulphuricacid with a glycerine content. The voltage range isfrom 0-40 from the start to the end of the first quarterhour, and 40-5o for the last to minutes. Assumingall precautions are taken, e.g., cleaning thoroughlybeforehand, washing thoroughly afterwards with cold,and later, hot water, followed by drying, and the processis thoroughly understood, e.g., the need for gradualrise of voltage as the anodizing progresses, we see noreason why you should not achieve success with theequipment mentioned. You will probably experiencetrouble, however, if you try to anodise alloy metalscontaining over 5 per cent. copper or high in silicon.

The following table will show you the correct voltageregulation.

Time Voltage

1st 15 mins. 0-4016-5o 4051-55 ,, 40-5056-60 5o

You will get improved corrosion resistance if youpaint and enamel the parts after they have been anodised.

Matt Black PaintT HAVE made an episcope and wish to paint the

inside with matt black heat -resisting paint.Can you advise me of the type and from whom itcan be purchased ?

Also, can you tell me how the crystalline lacquerfinish, used so much for the outside of metal instru-ments, is done ? If there is any alternative heat -resisting (outside) finish you could recommend, Ishould be glad of details.-A. Holdsworth(Nottingham).

ESSRS. JOHNSON & SONS, ManufacturingIv+. Chemists, Hendon, London, N.W.4, make agood matt -black, heat -resisting paint for fine instrumentwork such as you describe. You should be able toobtain such " matt -black " varnish from any photo-graphic suppliers. We believe, also, that Messrs.Flatters and Garnett, Ltd., Oxford Road, Manchester 13,make a similar type of varnish,

NEWNES PRACTICAL MECHANICSIn order to obtain a crystalline exterior finish, you

must add a solution of a metallic soap (such as aluminiumstearate) in acetone to your black lacquer and thensubject the lacquered article to heat in an oven. Since,however, acetone is quite unobtainable by the ordinaryuser, we do not think that you will be able to`work thisprocess. Why not write to Messrs. Johnson & Sons,mentioned above, in order to ascertain whether theycan supply a ready-made lacquer of this " crystallinetype ?

Most of the black external finishes to which you referare stove enamelled, that is to say, they are baked atfairly high temperatures, a process which is verydifficult to imitate on the small scale.

Waterproof Poster PaintCOULD you plEase tell me how to make ordinary--' poster paint waterproof and still retain thematt finish? I believe bichromate of potash hassomething to do with it. The type of waterproofposter paint I require is one that can be thinnedwith water, yet stand up to outdoor use.-P. R. Alderwick (Haverfordwest).QUITE a simple method of rendering poster paints

(water base) waterproof is to incorporate about5 per cent. of a good quality casein glue in the paintmix. A casein glue for this purpose may be obtainedfrom Messrs. J. Beard and Co., Great Ancoats Street,Manchester. The paint becomes waterproof a fewhours after being laid on the surface.

Another method is to incorporate about 3 per cent.of gelatine in the paint mix, and, when this has dissolved,to add about per cent. of ammonium, potassium orsodium bichromate. This mixing operation must beconducted by artificial light. The insolubility of thispaint is acquired after it has been exposed to light forsome hours, the bichromate, under the action of light,rendering the gelatine absolutely insoluble. If toomuch gelatine is employed, the paint will dry shiny;if too much bichromate is used, a strong yellow color-ation will result. Paint containing bichromate andgelatine must be kept in the dark when not in use,otherwise it w:11 gradually solidify.

Booster Cell for Charging CircuitT HAVE a 12 -volt lighting set with the dynamo

at some distance from the battery, and whenthe dynamo is charging, the voltage to the group

LocalLamps

Dynamo 2 WaySwitch

Battery

Circuit d'agram of a charging circuit showingsnitch for booster cell.

of bulbs situated at the dynamo house, etc., isabout 13.5 volts. Therefore I need a booster cellin series with that light group to reduce the voltage1.5 volt. Could'I make this cell and if so, how ?Its maximum load is 6 amps.-A. Spence Downby).THE simplest way of dealing with your problem

would be to run a separate wire from the dynamohouse to the end -.cell of the battery. A two-way switchcould be used to feed the local lamps from either 5 or 6cells as required. Another method would be to fitanother brush on the commutator of the dynamo insuch a position that the voltage between this brushand one of the main brushes is 12 volts when the mainbrushes give 13.5 volts, and feed the local lights fromthis. You could, of course, use a reversed accumulatorcell in circuit with the local lights, this would have acapacity of about 60 ampere hours ; but as this would becharged up when the local lights were used you wouldhate to make some arrangements for discharging the cell.Another method would be to use a separate resistancein circuit with each local lamp, together with a two-way switch to cut out the resistance when not required.Each resistance should have a value in ohms equalto t.5 divided by the lamp current.

December, 1944

Composition for Covering FloorboardsT HAVE an upstairs room which was used for

lumber, but I now wish to convert it into asitting -room -workshop for my own use. The floorjoists have weakened and the floor is sunk in themiddle and very uneven, so I would be muchobliged if you will give me particulars of aninexpensive mixture which I could make andapplyon top of the floor boards and leave to dry andset hard like cement.-W. E. Berney (Cootehill).IF, as you say, the joists of your floor have weakened,

there must arise the question of whether they willbe able to support any additional weight, consequentupon laying a coating of composition over the boards.This is a matter which can only be decided afterexamination.

The best composition which you could apply to yourfloorboards is a hard asphalt flooring mastic, but thisrequires special skill for its laying and, moreover, it is,in consequence of recent restrictions, unobtainable bythe ordinary person.

There are two alternative mixtures which you coulduse, although we cannot guarantee that you will beable to obtain adequate supplies of the necessarymaterials. The first of these mixtures has the followingcomposition :

Sawdust 40-60 parts (by weight).Cement 30-40Slaked lime 5 -to

The above mixture is kneaded into a paste withstrong waterglass (sodium silicate) solution. It is thentrowelled or " screeded " on to the floor and left toset.

The second composition has the formula :Bituminous emulsion 1.75 parts (by weight).Cement 1 part.Sawdust rCrushed limestone,

granite, brick orother mineral filler 4 parts.

This is laid in a manner similar to the precedingcompositions.

In either case, you should lay brown paper on thefloorboards and apply the composition on top of thepaper so that the layer of paper exists between the actualwood of the floorboards and the composition whichhas been laid down. The same technique should alsobe followed if an asphalt mastic is laid down.

Heating PowdersDEFORF the war one used to be able to buy

what might be termed " chemical hot-waterbottles." One of these consisted of a bag aboutSin. by 6in. in which was a powder. Upon theaddition of a few teaspoonfuls of water heat wasgiven out and when it began to cool down theaddition of a little more water was only necessaryto heat it up again.

I should be greatly obliged if you could informme what the chemicals inside were and in whatproportion they were mixed ?-M, Whitehead(Uppingham).THE " heating powders " to which you refer are

complicated to make, and they do not always worksatisfactorily or reliably. However, here is a formulaof such a powder :

Fine iron filings . ,

Ammonium chlorideMix the above ingredients thoroughly. Then add

1,,16 oz. of the following mixture :Manganese dioxide .. 10 oz.Calciuni chloride ..Iodine (or thymol).. .. .001 or.

The above powder heats up on the addition of water.A rather better heating substance is the following:

Sodium acetate .. .. 135 gramsGlycerine .. . 4.5 ,,Sodium sulphate. Cryst. .. 3.oSodium sulphate. Anhyd. .. 6.7

The rubber container holding the above mixture isplaced in boiling water for not more than to minutes.After that time the substance will be found to havebecome partially liquefied. During its recrystallisationand solidification, the substance will give off heat at acomparatively even temperature (about a to to 115 deg.F.) for about an hour, after which time its activitycan be renewed merely by placing the container inboiling water again.

' THE P.M. LIST OF BLUEPRINTSThe" PRACTICAL MECHANICS "120 CAR

(Designed by F. J. cAmm),10s. 6d. per set of four sheets.

" PRACTICAL MECHANICS " MASTERBATTERY CLOCK*

Blueprints (2 sheets), 2s.The "PRACTICAL MECHANICS" OUT.

BOARD SPEEDBOAT7s. 6d. per set of three sheets.A MODEL AUTOGIRO'

Full-size blueprint, Is.

SUPER -DURATION BIPLANEFull-size blueprint, Is.

The I-c.c. TWO-STROKE PETROL ENGINE* Hff=

Complete set, 5s.STREAMLINED WAKEFIELD

MONOPLANE -2s.LIGHTWEIGHT DURATION MODEL

Full-size blueprint,blueprint, 2s.P.M. TRAILER CARAVAN*

Complete set,10s. 6d.P.M. BATTERY SLAVE CLOCK* Is. a

The above blueprints are obtainable, post free, from Messrs. G. Newnes, Ltd., Tower House,Strand, W.C.2.

An * denotes *that constructional details are ovailo!ile, free, with the blueprint.

December, 1944 NEWNES PRACTICAL MECHANICS 105

Moulding CompositionCOULD you please supply me with a formula

for a compound for making book -ends,plaques, statuettes, and similar articles ?

I find plaster of paris will not stand roughtreatment.-T. Winship (Ilford).THE simplest material which you can use for book -end

making is ordinary cement mixed with a suitablegrit, such as white sand, or crushed silica rock and,perhaps, coloured by the addition of a little suitablepigment.

A good mix would be the following:Portland cement 6o per cent.GritPigment (iron oxide, chromium

oxide, etc., ochre) .. toThis mix would have to be moistened with water and

then packed into wooden moulds. After setting, thesurfaces could be ground smooth and then semi -polished.

Alternatively, you could use a magnesium oxychloridecomposition, such as the following:

Calcined magnesite .. 6o per cent.Grit .. 30l'igment or other " filler," (includ-

ing sawdust, if desired).. .. toThe above is moistened with a 40 per cent. solUtion

of magnesium chloride and the resulting paste is packedinto moulds. This composition takes two days to setand four days to harden, but it gives very sharp impres-sions, since it expands slightly on setting.

Metallurgical AnalysisCOULD you advise me on the choice of a book

dealing with such modern developments Inmetallurgy as analysis by (a) electrolytic means -1 understand that the sample is dissolved in acidand then plated out on to a platinum wire ; (hicolorimetric means, where the depth of colourof the solution in which the metal has beendissolved is measured by electrical means by aninstrument not unlike a photographic exposuremeter 3-K. N. Martin (Stanmore).VOU will find in the second edition of " Steel

Manufacture Simply Explained," by Gregory andSimons (Pitman, 7s. 6d.), a complete chapter onmodern developments in the metallurgical analysis offerrous metals. 'This is written in_a manner designedfor comprehension by either layman or engineer. Itdoes not deal with the electrolytic method of analysis,which is mostly u=ed for determining the oxides inferrous materials. The principle of the method is thesame as the chemical solution method in that themetallic constituents are separated. from the non-metallic, and the oxides determined in the residue.The specimen constitutes the anode of the cell, and theelectrolyte decomposes all non-metallics except theoxides. A complete account of the washing andanalytical procedure will be found in a paper by T. L.Joseph on " Oxides in Basic Pig Iron and in BasicOpen Hearth Steel," in the "Transactions of the Ironand Steel Divisions of the A.I.M.E. for 1937," vol.125, p. 204.

Obliquity of Connecting RodCAN you give me the formula dealing with

steam-engine connecting -rod length for agiden stroke ? In my particular case with thestroke of 15 x6in. I cannot determine how longthe connecting rod should be between centresto give equal movement of piston either side ofmiddle position due to obliquity of connectingrod.-A. Price (Birmingham).WITH any length of connecting rod the piston is

not at the mid -point of its stroke when thecrank. is perpendicular to the direction of motion ofthe piston.

If r= crank throwI=length of connecting rod

the error in position of tfie piston when it should beat the mid -point of its stroke is

I -1/(12-r )ra

and this is approximately RThe only way of getting no error is to use a connecting

rod of infinite length, which is inmraticable. In nonormal steam engine is the error of any importance.

Melting Scrap BrassT SHALL be obliged if you will advise me on-I- the following. I want to melt some scrappieces of brass, up to about six pounds, to be castas small bearings, and would like to be able toattain a heat of up to 2,000 (leg. F. '

I presume a small crucible would be necessary ;if so, where can I obtain this and of what materialis it best made ? How best could I obtain thisheat-by furnace or electricity ? I would also beglad to know of any books on the subject.-S. A.Booth (Belfast).PRESUMABI,Y the quantity of brass you wish to

melt is not large, in which case you will probablyobtain excellent results from a small oil -fired tiltingfurnace, which will melt isolb. of brass, with an oilconsumption of r4lb. per toolb. of metal. Largerfurnaces of this type can, of course, be obtained. Asmall furnace of this type will give to melts per eight -hour shift. It is, of course, possible to use lift -outcrucibles, heated by coke, or by producer gas (wherethere are several crucibles). The single-phase Detroitelectric furnace can also be used for melting brass,hut would hardly be economical for a small quantity.We suggest you write to the Morgan Crucible Co.,

I.td., Battersea, London, and put your problem upto them. A good book is " Industrial Heating Furnaces,"published by Chapman and Hall, Ltd., London.

Overshot Water -wheelT AM using an overshot water -wheel for driving

a dynamo for charging accumulators andobtain approximately 30 watts output. The wateris conveyed to the wheel by a sin. pipe, and theavailable fall is 4ft. bins. ; the normal flow isas cu. ft. per minute.

Which type of turbine would, be most satis-factory, and can you suggest a suitable design orany book which would give details for so small apower':-G. M. Whiteley (Shipley).

THE figures quoted suggest that the water -wheel isgiving an efficiency as high as could be expected

from a turbine for such a small output. For thecomparatively small head of 4ft. 6in. a vertical -spindleaxial -flow water -turbine may be recommended as themost suitable type of turbine, but there is no certainty that it would give any higher efficiency than is beingobtained at present. We do not know of any book thatgives practical design details for small turbines, butcertain types are made by Stuart -Turner Ltd., Henley-on-Thames.

Rewinding D.C. Motor for A.C.WILL you please answer the following queries:

1. I have a small motor which runs off250 volts D.C. How can I! rewind this to run off230 v. A.C.? The armature has 8 'slots, and thefield is of the two -pole type. Can this be madeinto an induction motor ?

2. How can I make a self -rectifying vibratorconverter to run off 230 v. A.C. having an outputof tzo v. D.C. ?-M. Clift (SkegnesS).

IcFomthpeletWelly011eamflienladteiA-oLsy4Itaeginoef motor5croouulrdbeu ised

as a series motor, the speed of which will vary with theload driven. If the motor has series field coils at present

p

J

ci

DC. Output

Circuit diagram of a vibrating rectifier.it is possible it will operate on 23o volts A.C. withoutmoditicatipn, or at any rate with about 3o per cent. ofthe present field turns removed. If it has a shuntfield at present these coils will have to be rewoundwith fewer turns of thicker wire connected in serieswith the armature. The armature should not requireany modification. If you will forward a fully dimensionedsketch of the field iron system, including the air gapclearance between the armature and field poles (whichmay be measured by means of feeler gauges) we willlet you have suggestions for winding the field coils.It would be a very difficult matter to convert the machineinto an induction motor.

(2) It will be understood that the unsmoothed outputof a vibrating rectifier is not at a constant voltage.The components of such a rectifier are a transformerhaving a ratio of about t to r, this preferably havingtappings for voltage control ; a centre tap being broughtout from the secondary winding. An electromagnethaving poles at A and B, as in the sketch, must be fedwith current at supply frequency; a light permanentmagnet NS having flexible spring contacts C and D issuspended by a flat spring as indicated. The polarityof the poles A and B is reversed each half cycle so themagnet swings in synchronism with the supply to closecontacts CE and DF alternately. The period of contactclosing can be adjusted if E and F are mounted onscrews.

Using Electric -Motor as WindchargerT HAVE a two -pole shunt-wound electric motor

rated at 36 volts, 3 amps, 1,800 r.p.m. It Isvery well made and has ball races.

I am considering using it as a windchargerdynamo, but realise that its output at wind -propeller speeds would be very small. Whatoutput might be obtained ?

I have been told that if I connect the two fieldcoils each in parallel with the armature brushes Ishould be able to get the following outputs. Canyou say whether they are approximately correctand if so, would the present windings be capableof carrying the current ?

With two field coils and armature all in parallelwith each other :

Output at 000 r.p.m., ma volts 6 amps.Output at 600 r.p.m., 8 volts 4 amps.Output at 300 r.p.m., 4 volts, z amps.

I also understand that the output of a shunt-wound motor when used as a dynamo at the samespeed is two-thirds of input as motor. Thus, asmotor, 36 volts 3 amps, ',Soo r.p.m. As dynamo,24 volts, 3 amps at r,800 r.p.m. Is that correct ?-F. Hewlett (Yelverton).

THE actual current output obtained from a dynamois equal to the terminal voltage divided by the

resistance of the circuit, assuming there is no backvoltage in the external circuit. This is subject to thefact that the safe full load current which can be deliveredwithout dangerous overheating depends on the size ofthe armature conductors and is therefore the same atall speeds and voltages, subject to a slight reductionat low speeds due to reduced ventilation and cooling.'Therefore you could not obtain more than 3 amps out-put.

With a given machine the generated voltage isproportional to the magnetic field strength and, with agiven field strength, is proportional to the speed. Itis advisable to retain the magnetic field strength as nearas possible to its original value, which means that thecurrent through each field coil should be kept the sameas at present. To obtain this the two series connectedfield coils could be connected in parallel when themachine is run on half voltage by reduction of speed.'Take care that the field coils are connected to createpoles of opposite magnetic polarity. Since there is acertain volt drop in the machine owing to its resistanceand armature reaction the machine should be run atrather more than half speed to obtain half voltage.Therefore, if you run the machine as a dynamo at, say,r,000 r.p.m., and connect the two field coils in parallelyou should obtain about t8 volts 3 amps.

It is difficult to say what voltage would be obtained ifthe machine is run at less than r,000 r.p.m., as thiswill depend on the design of the machine. If it wasdesigned to run with the field magnets saturated, thevoltage just below x,000 r.p.m. would be proportionalto the speed, i.e., about 14 volts at Roo r.p.m. Withunsaturated fields the voltage would be much less, asthe field current falls with reduction of generated volts.In any case the voltage would fall almost to zero withany appreciable reduction of speed. -

If it is essential to run the machine at less then about1,000 r.p.m., the field coils would have to be rewoundwith fewer turns of heavier wile than at present, sr)the product of the increased current and reducedturns would give the same ampere turns as at present.The resistance of the new field winding would have tosatisfy the condition that the resistance of the fieldcircuit multiplied by the required field current gives thegenerated voltage. Provided the ampere turns are thusunaltered the generated voltage would be directlyproportional to the speed. If at the low speed thegenerated voltage is too low, the armature would have tobe wound with more turng than at present. Withthe same field strength as at present the armatureturns would govern the voltage, since voltage is pro-portional to the armature turns in series. If the arma-ture is wound with more turns smaller wire wouldhave to be used, and this would reduce the safe fullload current.

Metal -rubber BondingIDO a considerable amount of pin grinding on" special machines which, up, to a year or soago, were reasonably free from trouble. Recently.however, I have had endless trouble owing to therubber strip coming loose off the metal saddle.I have tried various adhesive solutions in order toovercome this, but cannot get a rubber to stayput for more than a few hours after being putinto service. it appears to be well stuck to beginwith, but the heat generated by the process ofgrinding seems to soften the adhesive, with theresult that the rubber soon comes loose and failsto hold the pins in position.

Of course, the rubber I have to use now is notup to the usual quality, and it is possible that thisis the cause of my trouble.-R. Lister (Dewsbury).THE really satisfactory adhesion of rubber to metal

often presents difficult problems, particularly inthe instance which you quote in which the rubber -metal bond is continually subjected to strain. Youmay be quite sure that the actual rubber which you useis not at fault, since even the highest quality rubberwould give rise to the same trouble.

Strangely enough, the nature of the metal appearsto have some influence upon the strength of the bond,brass (and in particular, a 75 per cent, copper, 25 percent, zinc brass), giving by far the best adhesion.However, in your case, we imagine that you cannotdetermine the nature of the metal to which the rubbermust be bonded, and the advice which we give belowapplies equally to all types of metals bonded to rubber.

Good metal -rubber bonds may be obtained by theuse of bitumen and rubber solutions. Dissolve ordinaryhard " asphaltum " in either benzol or naphtha until afairly thick, creamy solution is obtained. Smear athin layer of this solution on to the metal surface,and, at the same time, smear a thin laver of thick rubbergolotion on to the rubber surface. Allow these respectivesolutions to dry out to the tacky stage. Then place afairly substantial layer of the rubber solution on to thebitumened surface of the metal, and, likewise a coatingof bitumen solution on to the rubber-solutioned surfaceof the rubber. Allow these respective surfaces tobecome fairly tacky. Then, if possible, dust one ofthe surfaces with flowers of sulphur. Bring the surfacesinto firm contact (under light pressure if possible) andallow them to remain undisturbed until dry.

The bond thus produced shoold be reasonablyenduring. In the event ofmuch heat being evolved, thesulphur will combine with both the bitumen(" asphaltum ") and the rubber, these materials therebyundergoing a species of vulcanisation and therebybecoming tougher.

Another mode of effecting a bond consists in rubber-solutioning both surfaces, and, at the tacky stage,introducing a casein cement (of which there are severalProprietary makes) between the prepared surfaces,contacting these under pressure for about 30 hours.

106

MODELSANCIENT & MODERN

If you are interested in ModelRailways, Ships, AircraftEngines, Weapons of War,etc., send 3d. and unstamped,addressed envelope for Illus-trated List of over 15o plans anddetails of our ConstructionalInstructional " Planbooks."'MODELCRAFT LTD.,77 (P.M.), Grosvenor Road,

London, S.W.i

add theFINIStiN6Touts-

. . . . to your models withPlasticine,' the famous modelling

medium. For nearly half acentury Plasticine ' has beenused by modelling enthusiasts theworld over, and to them at least,this material of 101 uses is indis-pensable. Supplies are strictlyrationed so make your Plasticine 'last.

HAR BUT T'S

Plasticine

NEWNES PRACTICAL MECHANICS

/ /40 YEARS' reliable service to the industry

MYER PER CONTROL LTD.CAMBRIDGE ROW, BURRAGE ROAD,

WOOLWICH, LONDON, S.E.I 8.

Electrical and MechanicalEngineers

Makers of VARLEY Products

1111.0.1

BOLT DOWN THAT MACHINE IN HALF THE TIME

with CINCH Bolt AnchorsSuitable for all fixings to walls, ceilingsand floors of cement, brick, stone, etc.

No delay : full load can be appliedimmediately. Depth of hole

40% to 60% less than ordin-ary fixing methods. Cinchanchors give a quick andpositive bite that holds per-

manently. Will not slacken orwork loose. Sizes to suit all

IMMEDIATE DELIVERY.needs.

Free ! SAMPLE AND DETAILS 01 RECEIPT 07 TRADE CARD.

HOYT METAL CO. OF GT. BRITIAN, Dept.P.M., Deodar Rd., Putney, London, S.W.15

IIIGII GAIN SOUND EQUIPMENT

A new range of A.G. and Universal Amplifiers are available includingspecial Units designed for Industrial Canteens, Schools, Military Camps,etc. These can be supplied with Radio Feeder Units. Complete Factory

Installations undertaken. Hi Gain A.C. Amplifiers, 18 watt, £25 ; 30

watt, £30 ; 60 watt, £40. A.C./D.C. 15 watt, CIS ; 30 watt, £25. Indus-

trial speakers, 8in. to 18in., and horn types.

SEFTON49, CLIFFORD AVENUE, LONDON, S.W.I4

(Telephone : PROspect 2889.;

SS

8/6d.Post & Packing 6d.

Complete in Case.4/so

5 In. scale, model cornplete in case.

ONLY.4/6 Post & Packing 4d.

Including Compiehensive SlideRule Book.

Approval or money refunded.

BRITISH SLIDE RULE CO.. (1)((at:)Proprietors: Marine & Overseas Services (1939) Lid.16, BARTER STREET. HOLBORN, LONDON, W.C.1. (Tel, Hol. 038))

DE LUXE" SLIDE RULESAN IDEAL XMAS PRESENT

12 inch log -log sin -tan rule,9 scales, for all problems.

Celluloid faced on polishedmahogany. Multipli-

cation, division, pro-portidn, percent-

ages,. discounts,roots, weights,

measures,currencies,

etc.

RAPID ANGLEINDICATOR

Solves at a glance allangles, sides of a rightangled triangle. iv

Post 3d.

THREAD CHARTThreads per inch. Whit-worth. B.A., and Gastapping -clearing sizesfor threads. Standardsizes, decimals, wiregauge,

Post 3d.

millt-metres, etc. 2/-

December, 1944

HIGHSTONE UTILITIESCRYSTAL SETS Our latest Model la

a REAL RADIORECEIVER, andis fitted with aP DR St ANENTCRYSTALDETECTOR.WRY NOT NAVEA SET IN YOUR,OWN ROOM ORAS A STAND-BY ?

-9/6, poet 6d.PERMANENTDETECTORS, 2/6,

post 3d..0005 Preset Condensers 2/-. post sd.

MICROPHONESJust the thing for impromptu concert., room tomom communication, etc. Bakelite table model,6/9 ; Suspension type, Le. Post 6d, Super Modelon stand. 12/6. Fitting instructions included.Mike buttons, 2/6. Transformers, 6/6. PublicAddress Trankverse current Mike, 3716, post 1/-.

BUZZERSNo. 2. Square single coil model, 2/6. No. 3.

Bala- DUTY double coil, 6/9, poet 3d.

MORSE KEYSPractise on a regulation site Tapping Key. Ourheavy brans model is mounted en a wooden base.has an adjustable gap and nicIel contacts. Key iswired to work buzzer or flash lamp by using a 41.voltbattery or the transformer described above.BRASS KEY 6/9, Chrotohuu plated, 7/6. W.O.Model with heavy brass bar and the addition or afront bracket, 0/6. Chromium plated, 10/6. Theabove keys are supplied to the Services for MOMinstruction. Slightly smaller Key, 4/3 Junior Key,mounted on a bakelite base, together with a hover.

Should you require a complete outfit, our D.X.2net. eomilsts of a heavy key mounted on a largepolished board. Win. a Woo together with a boozer,flash lamp, bulb mid holder, with two switches toMing either into cireuit. Terminals are also providedfor distant s/ toting and receiving, 1916, pest 8d.

BELL TRANSFORMERSThese guaranteed trans.formers work from anyA.C. Mains, giving 3, f.

or S volts output at Iamp., operate bulbbuzzer or bell. Witsupply light in bedroomor larder, etc. PRICE6/6. PO4T 5d.

SOLDERING IRONS, Adjustable Bit. all partsmplacea hie and fully guaranteed. 200/250 v.,

60 watts, 9/6: Ise watts 12/6. punt ad.SEND id. S. A. E. FOR LIST B.P. OP USEFULELECTRICAL ACCESSORIES. Money refunded Ifnot completely satisfied. Letters only. Pleaseinclude postage, any excean will be refunded.

IlIDHSTONE UTILITIES58. New Wansterid. LONDON. E.11

35FIRST PLACESAND HUNDREDS OF PASSESin the A.M.I.C.E., A.M.I.M.E., A.M.I.E.E.,A.F.R.Ae.S., A.M.I.Chem.E., C. & G., etc.,Exams. have beenr gained by studentsstudying a; home with the T.1.0.0.Engineering First Places are your bestguide to the most successful EngineeringCourses. Write to -day for " The Engineer's.Guide to Success," containing the world's

widest choice ofEngineeringCourses - over200 = coveringall branches -Me chant cal,Electrical,Aeronautical,Wireless. CivilChemical, etc.'and which alonegives the Regu-lations govern-ing admission tothe RecognisedInstitutions.TheT.I.G.B. guaran-tees traininguntil successful

The TECHNOLOGICAL INSTITUTE, OFGREAT BRITAIN,

218, Temple Bar House, E.C.4.

World's best choice ofCourses in Engineering

JUBILEE WORM DRIVEHOSE CLIPS

The long -lifeclip with the

ever -tightgrip

The Best KnownFor

Radiator Joints,Air, Oil andWater Hose

JointsWe guarantee a

Tight JointL. ROBINSON & Co.

25. LondonChambers,

CILLINGLIAM.KENT

December, 1944

ELECTRADIX-__.FOTO " COPY CABINET for prints,

blue, white or photostats up to 24in. byI7in. horizontal printing on glass platetop. Steel Case 2ft. Sin. by Ift. 7in. by2ft. Sin. high, with pad lid. Fitted 8 lampholders, dimmer slide rest and time switch.Bargain £5/1716.

MOTORS. A.C. Motors for 2001250 voltmains, 50 cycles, new, 1,425 rev., enclosedtype, 1 H.P. and .1. H.P. Quick deliveryfrom limited stock.MOTOR PUMPS. We can give immedi-ate delivery of the famous Stuart Turner12 -volt D.C. motor pumps ; 120 galls. perhour, 841-. Same type, but for A.G. mains,1361-. Pumps only : R type twin -pistonrotary for h.p. motor drive, f3151-.Aquarium aerators, £5.FUME EXTRACTOR AIR PURIFIERS,25 cub. ft. approx., with large filter chamber,all steel, 151in. x 201zin. x I4in., with intakedown shaft. Geared hand drive or 116thh.p. motor. Suit laboratory or works.SWITCHES. G.P.O. Lab. Switches, D.P.,fine job, up to 10 amps. reversing, 4in. base,716. Knife A and E type, single pole C.O.,116. Double pole On -Off 119. Double poleC.O., 216.. 100 amp. S.P. with fuses, 2216.200 amps., 401-. 5 amp. ironclad tumbler.219. Linked tumbler, 5 amps., 216. 10amps., 312. Multi -contact R.I. 7 -stud 5 amp.on ebonite panel, teak box base, 41in,4lin., 716. Lucas 6 -way lever handles inline with box back, 31-. Ditto 8 -way, 319.6 -way push-button A.M., 219. Rotary Hartsnap switches, 2 -way or.On-Off, 10 amps.,41- ; 15 amps., SI-.

BUTTON MICROPHONES !Thousands use these wonderfully ingenioussolid -back SOUND TRANSMITTER UNITS.The lin. dia. brassbody is of solid brass,forming the granulechamber, and thediaphragm is thin mica.Experimental uses forthe Button : HomeBroadcasting, Detec-tors of Sound for AirRaid, Baby Alarm,Leaky water mains, Electrical Stethoscopesor Vibration detectors,EVERY BUTTON TRANSMITTERWE SUPPLY IS GUARANTEED.

PRICE ONLY 216 (Postage 6d.).High -ratio Transformer for above, with

all instructions, 416.EMERGENCY CRYSTAL SETS. TheWALL NUT crystal receiver for table orwall. Tapped A.T.I. tuning condenser, inpolished walnut case, 421-. The B.B.C.BLACKBIRD set, porcelain base, steelcover, 39/6. The SHERMAN TANK hassame tuning as " Wall Nut," but novelsteel cover, 451, MARK II Het. Convertedex W.D. wavemeter with 2 detectors,91in. x 71in. x 551-. HEADPHONES,1716.

CONTROL BY LIGHT andInvisible Rays. Raycraft setswith selenium bridge. 10,000

ohms tele-type Relay, fittingsand booklet, 421,

RHEOSTATS " AETNA " panel switchrheos. to 1 ohm and off, 6 volts 3 amps.,with bulb in knob, 216 each, postage 6d.Slider rheos. for all currents ; heavy grid40 amp. 10 -stud control, 240 volts to 45volts, 33in. x I6in. x I4in., £51101- ; smallerfor 110 volts to 45 volts, £31101-. PitkinLab. rheos., circular Bin. glass front, 50ohms 2 amps., 351-.

CONDENSERS. UltraShort Wave variable aircondensers. Trolitulinsulation ball -bearings.Surplus to a Govt.contract and new, St-

G.P.O. Lab. Switches D.P. reversing formodel control, motors and test work, 716.MAGNETS. We Save a large range ofpermanent magnets. All sizes from 2 ois.to 4 lbs. Stamped envelope for leaflet.Electro-magnet Solenoids, for 12 voltsD.C. with 2in. free plunger tin. dia.,compound wound, 616.

Please include postage, for mail orders.

ELECTRADI X RADIOS214, Queenstown Road, Battersea,

London, S.W 8

Telephone MACaulay 2159

NEWNES PRACTICAL MECHANICS 107

PELMANISMFor All TimesINSTRUCTION IN

PLASTICS TECHNOLOGYA NEW organisation has been formed to supply

ambitious people interested in the PlasticsIndustry with modern instruction in PlasticsTheory and Practice.

The new organisation, known as The BritishInstitute of Plastics Technology, is the specialistPlastics Division of The British Institute ofEngineering Technology, Ltd., one of the largesthome -study technical training organisations in theworld.

Specialist Plastics Courses are being preparedand will be available within a reasonable period.Those interested are advised to submit theirnames and addresses, when a copy of our Prospectus" OPPORTUNITIES IN PLASTICS " will beforwarded as our tutorial plans mature. Enrolmentfor the special courses will first be offered to thosewhose names have been thus recorded, but noobligation whatsoever will be incurred in lodgingan application.

BRITISH INSTI'llUTE OFPLASTICS TECHNOLOGY

4, Shakespeare House,17-18-19, Stratford Place, London, W.1

" SHAW" DIRECT CONVERSION PROTRACTORAND PARALLEL RULE

(Pray, Potent No. 17353 42).

Simplifies and accelerates the conversion of bearings toor from Maps and Charts.

Principal uses :I. To obtain grid bearings on map or chart and convert to compass bearing.2. To convert compass bearings to grid bearings.3. To convert compass bearings to grid bearings and plot on map or chart.

Each instrument supplied with full directions.

Stocked by all leading retailers.

An I.D. Product. Finest indestructible.Made in England. Thermo -plastic material.

INSTRUMENTAL DEVICES, LTD.,7, Charlotte Mews, Tottenham Street, London, W.I

YOUcan lwcoine a first-classRADIO ENGINEER

PcAtoupon now for free booklet and learnbovf yeu can qualify for well -paid employ -Mint or profitable spare -time work.

We are specialistsin ., liome-StpdyCourSes ift BackeN eeeptieir, Sinnkint, Trt ,mission,t oieviii Mat* 1 send me free details of youi Home -Study

'

fit rid gla.

Wok, ; Courses' in Mathenlatics and Radio.Ca eulatIo rt#* II Name

(P° ru I Addrminis wive ess

mi).) 31.17------- - - - -

T. & C. RADIO COLLEGE,2, The Mall, Ealing, W.5

and Circumstances

PELMANISMhas stood the

test of time. During the lasthalf -century, in peace and war, intimes of prosperity and of depres-sion, it has helped and encouragedmen and women in all the affairsof life. Now in this time of un-precedented happenings andsupreme efforts two facts standout against a background ofevidence -the large number ofserving members of H.M. Forcesenrolling for the Pelman Courseand the continued support ofthose not in uniform but heldclosely to civilian occupations.

Half fees for serving members ofHis Majesty's' Forces

(Apply for Services Enrolment Form)

This increasing demand provesthe creative and re -creative valueof Pelmanism. Minds under stressand strain are sorely in need ofrestful recreation and soothingstimulus. Pelmanism gives all thisand more. It is the way to clearthinking and calm but determinedaction under all circumstances.You cannot be harassed by anxie-ties, fears and worries, or feelhelpless, mute and fearful in timesof sudden emergency whenimbued and bayed up by thefriendly personal guidance ofPelmanism. Take the Course.to -day and possess those self-reliant attributes permanentlyenjoyed by over half a milliongrateful Pelmanists.

A True PhilosophyPelmanism is a true philosophy

of living for ordinary sensiblepeople vabo wish to make the bestof themselves at all times and underall circumstances. The PelmanInstitute has won and held itsunique position through all warsand worna, trials and tribulations,during the last half -century.To -day Pelmanism is appreciatedas much as ever. The test of timehas proved the Power of Pelman-ism and in these exceptional andever-changing times it plays itspart in the National Effort.Remember -Everything you do ispreceded by your attitude of mind.

The Pelman Course is fullydescribed in a book entitled"The Science of Success." TheCourse is simple and interesting,and takes up very little timeyou can enrol on the most con-venient terms. The book will besent you, gratis and post free, onapplication to :-

Pelman Institute,(Established over 40 years)

130, Albion House, New Oxford St.,London, W.C.1.

Readers who can cull at the Instihtte willSc welcomed.

PELIIAN (OVERSEAS)INSTITUTES:NEIV YORK: 271 North Avenue, NewRochelle. MELBOURNE; 396 FlindersLane. JOHANNESBURG: P.O. Box4925. DURBAN: Natal Bank Chambers(P.O.'Bps 1480. DELHI : 10 Alip.)reRoad. CALCUTTA : 102 Clive Street,

108 NEWNES PRACTICAL MECHANICS December, 1944

Remember those times . . .How many of these famous people do you recognisefrom the Hercules Team of 1939 ? Do you rememberMarguerite Wilson's magnificent London -Bath andback when she clipped over an hour off the record

and the faces?with an average of 19.4 m.p.h. ? Do you recall Cyril Heppleston's epic468 miles in 24 hours ? We publish this memorable photograph in responseto requests from cyclists everywhere, and only regret we cannot supply acopy to each one of you. That is impossible these days, but perhaps youwould like to cut out this reproduction as a happy reminder of great timesby great riders on a grand cycle - HERCULES.

Richard Kemps," Shake" Earnshatc,Marguerite Wilson,

C. Riga,Cyril Heppleston.

Hercules- CYCLES

THE HERCULES CYCLE AND MOTOR COMPANY LTD ASTON BIRMINGHAM

H.R.I

December, 1944 THE, CYCLIST 17

VOL. XIII

4 isViffs

Editor : F. J. CAMM

DECEMBER, 1944

Comments of the Month

TimeTHE R,T.T.C. has wisely made the

decision to announce next season'sprogramme earlier than hitherto to

enable the handbook with the full list offixtures to be published at the beginningof the 1945 season, not some time afterwards.

All the 1945 championships have beenallocated and this will enable clubs to arrangethe remainder of the 1945 trials accordingly.The championships have been allocated asfollows :

25 miles to be arranged by LiverpoolDistrict Council on week -end No. 16.

5o miles to be arranged by North MidlandsDistrict Council on week -end No. 24.

too miles to be arranged by Central DistrictCouncil (who have entrusted the pro-motion to the Broad Oak R.C. of Notting --'ham) on week -end No. 20.

12 hours to be arranged by London NorthDistrict Council on week -end No. 26.

Hill -climb to be arranged by ManchesterDistrict Council (date not yet fixed).

25 miles (women) to be arranged by Mid-land District Council on week -endNo. 18.

In view of the possibility of large-scaledemobilisation of clubmen during the 1945season, the regulation made last Februaryconfining , the championships to riders whohad completed a trial at the appropriatedistance during the three previous seasonshas been relaxed for 1945. Any rider whohas a trial to his credit at the distance of thechampionship event concerned will be eligibleto enter, but of acceptance will be givento those whose last ride at the distance wasperformed since January 1st, 1943.

To enable non -accepted entrants to the1945 championships to know the position intime to enter another trial, all championshipentries will close 19 days before the event.

The secretary or chief official of a champion-ship event cannot compete in that champion-ship.

A major change has been made in theconditions of the 1945 A.R. competition.Instead of being based on events at 25, 50and too miles, as in 1944, the 1945 competi-tion will comprise events at 5o and too milesand 12 hours.

On the dates of the men's 25 miles, 50miles, too miles and 12 -hours champion-ships, those championships will be the onlyevents eligible for inclusion in the competition.

Competition Records

HITHERTO no regulations for theserecords have been published. Pursuant

to the powers given them by the NationalCouncil in February, 1939, the NationalCommittee have adopted the followingregulation, which takes effect immediately,but the changes involved in these regulationswill not invalidate any claims pending forrecords already made :

The Council shall adjudicate upon claimsto have established record times in road trials

All letters should be addressed tothe Editor, "THE CYCLIST,"George Newnes, Ltd., Tower House,Southampton Street, Strand, London,

W.C.2.

Phone : Temple Bar 4363Telegrams : Newnes, Rand, London

Trial Plans for 1945under R.T.T.C. regulations at 25, 30, 50,too and zoo miles and 12 and 24 hours onbicycles, tricycles and (except at 25 miles)tandem bicycles by individual riders and teamsof three machines. The following specialconditions shall .apply :

(a) No claim shall be considered unlessthe performance to which it relates is madein an event in which members of to orinore affiliated clubs are eligible to takepart. Such event must have been approvedby the District Council beforehand havingjurisdiction, and a start sheet must havebeen issued to the participants in advanceand the claimant's name must have appearedthereon at the time of issue.

(b) The elapsed time for record purposesshall be calculated from the starting timeshown against the claimant's name on thestart sheet.

(c) In. the event of more than one claimto a particular record being submitted inrespect of performances on one date, thefastest time or greatest distance claimedshall first be considered and, if accepted,shall stand as record.

(d) No claim shall be considered unlessthe time -keeping arrangements in the eventconcerned complied with the standards laiddown by the Council for timekeeping inopen events, and the course is certified bythe District Council having jurisdiction ashaving been measured and approved inaccordance with regulation 27. Thedistance between the start and finish shallnot be greater than the following : 25 and3o miles, one mile

'5o miles, two miles ;

too and 200 miles, five miles. For 12 and24 hours events the course shall be of thenormal out -and -home nature.Claims to have made a competition record

shall be submitted in the first place to theDistrict Committee having jurisdiction. TheDistrict Committee shall investigate the claimand shall satisfy themselves of the accuracyof the times and measurements, the genuine-neSs of the performance and the compliancewith all relevant regulations. If satisfied,they shall then submit the claim to theNational Committee with their recommenda-tion. Throughout all processes the formsissued by the National Committee shall beused. The National Committee shall adjudi-cate on the claim, and their decision shall befinal.

The most important regulations broughtabout by these changes are that competitionrecords cannot now be made in single clubevents, nor by riders who enter at the lastmoment, and whose name is not on the, startcard. Another important decision is that alllate starts will be debited against the rider,and that a particular record cannot be awardedfor more than one performance on any oneday, that one performance being the fastestif accepted. These new regulations will;subject to approval by the National Council,be incorporated in the 1945 Handbook.

It has been decided to present championship

By F. J. C.

medals to all 1944 champions and placed ridersand members of championship winning teams,

1945 Fixture List

ALL open events for next season must bearranged and notified to the national

secretary by December 14th, 1944, otherwisethey cannot be included in the 1945 fixturelist. District Councils will make whateverarrangements they consider necessary toachieve this object, including the holding ofearly date -fixing meetings.

Post-war Problems of the Cycle Trade

THE British Cycle Manufacturers, at therequest of the Board of Trade, have

reviewed the problems with which they willbe faced when the war ends. They point outthat apart from auxiliary trades it is belidvedthat at the outbreak of war there wereapproximately 15o manufacturers of bicycles,32 manufacturers of motor -cycles, and zoomanufacturers of components and accessories,or materials for both machines. Two-thirdsof the manufacturers have been engagedchiefly on war work, and of these about adozen bicycle manufacturers and seven oreight motor -cycle manufacturers have beensupplying their respective products. It isestimated that within 12 months from theend of the war the output of bicycles couldbe increased to 6,000,000 a year for homeand overseas. Thirty-four cycle andcomponent manufacturers could resume peaceproduction at once. The position is moreserious with motor -cycle manufacturers.

In order to speed up reconstruction the .

following suggestions are made : Modificationof Essential Works Orders ; early return ofkey personnel; speedy reconstruction offactories ; availability of further tool -roomplants as war contracts end ; completeabolition of Purchase Tax ; cheap moneyfor buildings and plant ; freedom of exportmarkets from Lend-Lease restrictions ;acquisition of surplus Government plant atfair prices ; and Income Tax Concessions fordepreciation.

Bicycle manufacturers have not the desireto leave the Midlands, and are unable toconsider proposals for the removal of theiractivities to the depressed areas.

Considerable competition is expected afterthe war from bicycle assemblers in theDominion and Indian markets, particularlyif they adopt import tariffs. A continueddevelopment of sales is anticipated in theColonial Empire, where Japan was the chiefcompetitor before the war, and in WesternEurope, where competition from Germanywas particularly severe.

The Memorandum assumes that thepost-war manufacturing activities of bothGermany and Italy will be controlled with aconsequent revival of the European trade lostto Germany through the latter's policy ofundercutting by subsidies. It is also presumedthat Japan will lose her export trade.

18 THE CYCLIST

H. Mawby Prisoner -of -War

NEWS is to hand thatHarold Mawby,

Yorkshire Road Club, isa prisoner - of -war mGerman hands.

Stratford St. Mary, Suffolk.

A Welcome SightMILESTONES

have been replaced alongHuntingdon sections of the Great North Road.

A Proud RecordSERGEANT WILLIAM HENDRY, the third

member of the noted Hendry family of Glasgow,has been awarded the Distinguished Flying Medal for" skill and devotion to duty."

An Irish " 12 "T GRAY, Northern C.C., had the distinction ofJ winning the first open tz-hour event ever to beheld in Ireland. He covered 222 miles.

Bramley Wheeler's LossNORMAN HOLMES, of Leeds, former hon.

treasurer of the Brantley Wheelers, has died ofwounds in Italy.

1944 Best All-rounderA R. G. DERBYSHIRE, Callava Road Club, is the

R.T.T.C. Best All-rounder for 1944. He is alsonational 12 -hour road champion.

Seath RetiringL M. SEATH, well-known member of the

Vegetarian C. & A.C., and prolific road rider,has retired from competitive work. For the past ityears he had been an active time-trialist.

Hill Climb ChampionFH. WORTHEN, Manchester Clarion C.C.,

became Britain's champion hill -climber byvirtue of his win, with 3 mins. 12 415. seconds, of theCatford Hill Climb.

Pioneer DiesTows. OWEN, North Road C.C., whose son, Tom,.1 is very well known on North ILondon roads, hasdied. He was 84.

Veteran's Fine RideT B. AUSTIN, 43 -year -old Oxford City RoadJ Club member, was fastest in a veteran's 25 -mileevent with a fine ride of 1.6.54.

Chippenham's RevivalTHE revival of the Chippenham- Sports Club

Festival provided an excellent opportunity forsome fine track racing in which members of Bristolclubs prominently featured.

The Sailor's ReturnGEORGE DOWNES, Gateshead c.c.,- who had

been abroad for almost three Years, was marriedduring a- short leave.

Hebburn's Coming -of -AgeHEBBURN VICTORIA, C.C. celebrate their

coming -of -age in 1945.

After Three YearsCI H. BURGESS, Bronte Wheelers, is now known to

be a prisoner -of -war in Japanese hands. Ile wasreported missing almost three years ago.

Wong Ling Kwong's WinTN a ro-mile road time trial, promoted by the

All -Chinese Cycling Club in Liverpool, thewinning time was 20 minutes 4o seconds, and thewinner, Wong Ling Kwong, who rode a gear of 104.

December, 1944

Yiewsley R.C. News"pLEVEN members of"- the Yiewsley RoadClub are serving with theForces: two have beenreported missing. S.Euratt, serving with theFleet Air Arm, has beenawarded the D.F.C. Heholds his club's 25 -milerecord.

Killed in France\TICTOR FOREMAN,V

Norwood ParagonC.C., has been killed inaction in France.

Club Record BrokenRG. PEARSON has

broken the RedditchRoad Club's record of 34minutes 29 seconds for the

journey from Redditch to Bromsgrove and back.The previous holder was D. Gardner, who is nowserving with the R.A.F.

Colin Cameron KilledrLIGHT-SERGEANT COLIN S. CAMERON,-L. South -Eastern Road Club, lost his life in an aircrash. He was a fine rider, and gave promise of anexceellent road career.

De Laune C.C. NewsDH. EVANS, De Laune C.C., is now known to

be a prisoner -of -war in Germany. ClubmatePilot Officer G. W. Hinde has been posted as " killedin action " following a heavy raid over Duisberg.

Reunion in Italy .

FOUR members of the tynea C.C. have met inItaly. They are the brothers William and IsIwyn

Wheeler, R. T. Williams and W. Peters.

Wounded in ItalyT SIANGSBY, champion of Bramley Wheelers,-1-' has been wounded while serving in Italy.

Captain K. V. Hancock KilledAPTAIN K. V. Hancock, Yorkshire Road Club,C has been killed in action in France.

Fifty FlightsWILLIAM McMULLEN, Bournemouh Jubilee

Wheelers, a Pilot Officer in the R.A.F., has over5o operational flights to his credit.

Parachutist MissingAMONG those posted as " missing " following the

epic of Arnhem was Cyril Ayley, SouthernParagon C.C.

A Lost MedalWHOOPER, Swindon Wheelers, came through

Dunkirk carrying with him a club gold standardmedal. Later he lost it, but, two years after the loss,his club secretary was advised by the Chief Constableof Leicestershire to the effect that the medal hadbeen found. It has been returned to the owner.

New Dunlop PostMR. A. E. OSBORN, Dunlop acting general

manager in Manchester, has been appointedgeneral sales manager of a new Division for specialproducts, particularly of an industrial kind, withheadquarters at Albany Street, London.

Mr. Osbor% has been in the rubber industry sincehe began with the Silvertown Rubber Co. before thelast war, during which he was a pilot in the R.A.F.He joined Dunlop in 1926 as London manager of theMacintosh group.

Tyre Makers' SymbolA BADGE has been adopted" by the Tyre Manu-

facturers' Conference, repre-senting all British tyre makers.It is a simple design showingthe letters T.M.C. in boldrelief against a tyre in thebackground. The symbolwill be used on all Conference notepaper, publicationsor posters.

Evening at Tonypandy, Rhondda Valley. To the left is Llwynpia Mountain.

December, 1944 THE CYCLIST 19

Around the WheelworicLegislators !A LEGISLATOR is one who makes laws,

and it is therefore wrong even for theless informed of our critics to refer to thosein the higher positions in the cycling worldas legislators. They have never made anylaws (thank goodness !) although they liketo lay down the law. Some of these cyclingleaders and critics take on airs and graces.

Herne Hill Arrangements for 1945THE National Cyclist Union announce that

season training tickets for 1945 will cost15s., and evening training tickets 6d. Theyhave also settled the schedule of prices forhire of the ground, cabin fees, etc.

The S.C.C.U. will organise a meeting atHerne Hill on Good Friday, 1945, whilst theUnion itself is promoting a Grand Openingmeeting on Saturday, June 23rd. It isprobable that this meeting will be of aninternational character. The meeting ofchampions has been fixed for Saturday,September 8th, 1945.

C.T.C. ChangeAT the end of January, 5945, Neville

Whall becomes secretary of the C.T.C.,and R. Shaw the Editor of its Journal.

" Merrie England "A FIRST-CLASS presentation of Sir

Edward German's " Merrie England "is now showing at the Winter Garden Theatre,London. My reason for referring to it hereis that W. Hinds, in conjunction with ReginaldFogwell, has put the show on. Hinds is, ofcourse, the well-known cyclist who adoptsfor his theatrical enterprises the name ofWill Hammer-his business as a jewellerbeing located in Hammersmith. It is a showwell worth seeing, and is quite the bestperformance of this famous musical showthat I have seen..

Dinner to the Champions-THE committee of the London West

District Council of the R.T.T.C. gavea dinner at the Holborn Restaurant onNovember 8th to honour those members ofclubs in the London West area who are the1944 R.T.T.C. champions.

I list them, together with their per-formances : 12 hours, A. E. Derbyshire(Calleva Road Club), 233k miles ; too miles,A. C. Harding (Middlesex Road Club),4h. 28m. izsec. ; 5o miles, A. C. Harding(Middlesex Road Club), 2h. 6m. 35sec. ;25-5o and too miles, A. E. Derbyshire(Calleva Road Club), average speed overthree distances, 23.549 m.p.h. ; 12 hoursteam race, Calleva Road Club, who sharethe honours with Altrincham Ravens. Theteams of both clubs deadheated with adistance of 6841 miles. The Calleva teamwere : A. E. Derbyshire, R. Brown and W.Perkins.

Mr. A. V. Jenner (Charlotteville C.C.),chairman of the London West District Council,was in the chair on this occasion and proposedthe toast of the champions. There was aresponse from A. E. Derbyshire only, asA. C. Harding was unfortunately unable tobe present. There were speeches byF. J. Camm, H. England and Rex Coley.

R.T.T.C. and S.A.C.A. MeetingAMOST cordial meeting between repre-

sentatives of the R.T.T.C. and S.A.C.A.was held in Carlisle on Sunday, November 5th,to discuss the present position regarding an

By ICARUS

All -British Championship competition andthe possibility of formulating a schemefor an All -British competition, on a per-manent basis, which could commence in1945.

The S.A.C.A. representatives, having heardin detail the reasons which led the R.T.T.C. todecide that they could not entertain a com-petition in 1944, undertook to recommendto their association the discontinuance of theproposals they had announced regarding 1944 -

The representatives will place before theirrespective committees a scheme for an All -British Championship competition to com-mence in 1945, based on results at 5oand too miles and 12 hours. The adoptionof any scheme is, of course, a matter to bedecided by the membership of the twobodies, before whom it will be placed ingeneral meeting.

R.T.T.C:-N.C.U. Joint Statement/R. JAMES KAIN, the chairman of the

-"" London Section of the British Leagueof Racing Cyclists, comments as follows onthe joint statement issued by the R.T.T.C.and the N.C.U. on massed -start racing, andwhich was published in our last issue.

In the joint statement issued by theR.T.T.C.-N.C.U., dated October loth, 1944,it mentions " A number of people have brokenour rules and promoted massed -start racingon the public highway . . . these people havebeen suspended and our action has been over-whelmingly backed by the membership of ourbodies." Who are the " people " who havebeen suspended ? When were they suspended?

*For what crime were they suspended ? Ihave now personally contacted over too activeB.L.R.C. members who, including myself,have had no notice of suspension served(with its democratic right of appeal), nor hasany of our names been published in thepress. Is it that these would-be Law Lordshave realised and appreciated some of thefiner points of English Common Law, andtherefore dare not publish these names ?

Regarding the " overwhelming " backingof the R.T.T.C.-N.C.U. membership, whendid the R.T.T.C. obtain this " overwhelming "support ? I have yet to learn of any attemptby the R.T.T.C. executive to obtain theopinion of its adherent members upon thisspecific subject. Is it that they dare not riskthe attempt, to arrange a " public opinion "poll open to -the whole of their membership ?or is it that they prefer to shelter behind thenewly found champidn of road sport, theN.C.U., whilst this body of utilitarian cyclistsrattle the hollow bogy of suspension ?

I would emphatically remind this latterbody that the subject matter of the jointstatement concerns cycle road racing . .

since when has the N.C.U. started catering'for cycle road racing ? From where has thisassumed dictatorial authority over road mensuddenly materialised ? The only cycle racingover which the N.C.U. has control is pathracing on enclosed tracks, and having, bytheir ineptitude, ruined this sport, they nowhave the presumption to try to gate crash intothe road game. In each of the 10 -year periodssince 1888, when the N.C.U. outlawed theroad game (the nursery of future pathchampions, by the way) the N.C.U. Racingregistrations have consistently registered newlow records, and their 1939 Racing registra-tions figures have already been comfortablysurpassed by the wartime registered Racingmembership of the youthful B.L.R.C.

Mr. Chamberlin, who spoke at most ofthe poorly attended meetings at which the99.9 per cent. anti -massed start vote was

recorded (sounds like a Nazi plebiscite result).knows .only too well that throughout thewhole country a total of less than 5o registeredracing men attended . . . such is the " over-whelming " R.T.T.C.-N.C.U. backing r

Service Pay ConcessionTHE Dunlop Rubber Co., Ltd., has decided

that no deduction will be made fromthe Company's grants to their employeesnow in the Forces in respect of Serviceincreases in pay recently announced.

The Company's personnel will thereforereceive the full advantage of the new increases,which run from 7s. ,to 77s. a week for theJapanese campaign and from 2s. 4d. to '21s.a week as a Far East allowance, in additionto the war service weekly increment of from7s. to 21s. for three years' service, with anextra 3s. 6d. to 7s. for each year of service,over three.

C. A. Smith Passes

IT is with great regret that I record thedeath on Wednesday, October 11th, of

that famous cycling character, C. A. (Bathroad)Smith, at the age of 77.

As a personal friend of many years' standing,I keenly feel his loss. In the 'nineties, C. A.Smith, swept very nearly all before him ;

...and his vast array of cups and trophiespacked one room of his house at Cobhamwhere he resided, almost opposite that famousold coaching inn, " The White Lion," (ofwhich for many years he was proprietor) onthe Portsmouth Road he loved so much.

Equally good on bicycle and tricycle, hewon races and broke records in quicksuccession, and beat many of the giants ofthe sport of his day, including S. F. Edge.He had a vast knowledge of cycling history,and knew almost everyone associated withthe sport and the industry intimately.

Although at one time he owned severalcars, as well as a museum of earlymechanically -propelled vehicles, he neverdeserted cycling, and each day, with veryminor' exceptions, he rode from 3o to so miles.He kept a very accurate diary of all his rides,and his home was a store -house of cyclingbooks, periodicals and photographs.

As every cyclist knows, he maintainedthroughout his life that it was necessary tohave a first-class machine with properly cut

. chain wheels, and his own machine, whichis over 40 years old, is so equipped, and hasthe original chain and chain wheel on it.We lunched together once a week, and Ilearned a good deal of the early history ofthe sport from him. He once told me thathe owned one of the first pairs of pneumatictyres which came into the country, andevery time they punctured they had to goback to Dublin for repair. He was a fiercebut fair critic, and deplored the fact thatthe sport was not on the same high plane asit was in the last century. Almost up to thetime of his death he regularly attended themeetings of the Roadfarers' Club, of whichhe was a Fellow and member of the Council.

On the day of his death he had justcompleted a 20 -mile ride. I* passedsuddenly but peacefully away. There is noneed for me to detail the many races he won,for the story has been told many times inthis journal.

All of his papers and press cuttings arein my possession, and, as space permits,I shall deal from time to time with mattersof interest, and which have not hithertobeen published. He will be missed by manyhundreds, for he was a familiar figure onthe roads of the Home Counties.

20 THE CYCLIST December, 1944

East Hagbintrne, Berkshire.

New Prices?WE are now near enough to the end of this awful

-war to glance at the possible picture of the post-war world as far as our pastime is concerned. The firstitem to consider is the new cost of out bicycles, thebasic prices that will rule after the industry has gotgoing again. Pre-war that figure was k4-£3 19s. 9d.to be precise-and from that basis every other bicyclevalue was reckoned. Now it seems to me that such afigure cannot possibly return, quite apart from thequestion of Purchase Tax, which to -day stands at24 per cent. on the retail price. I imagine flag the oldconditions of employment will not return-will notbe tolerated --and wages cannot slump to the pre-warrates if we are going to enjoy that better world sowidely promised. Material will cost more, labour chargeswill be higher-and a bicycle is mainly a labour charge-and it is more than possible the dealer will need abigger discount from the manufacturer to meet hisincreased charges. As to what the new basic pricewill be I have no definite knowledge, but if it is withinthe region of £5 less tax then I think it will ,be onvery reasonable terms. I cannot conceive it being less,anyhow as far as the home market is concerned.

All-round AdvanceITHINK that a rise of 25 per cent. on the old figure will

be the all-round advance on every type of bicycle,and its equipment and accessories. Pre-war the S.A.3 -speed huh was listed at £1 extra ; in reason, wecannot expect that figure to remain. So with tyres,and brakes, and bells and pedals, chain -wheel sets,chains, saddles, touring bags, lamps, and all the h6stof extras that go to make the complete bicycle. If theadvance is no more than the suggested 25 per cent.we riders will be fortunate, for there will be few othercommodities, either in the travel sphere or the douse,that will he purchasable at so modest a rise over pre-warprices.

Many More CyclistsANY modest rise in the cost of bicycles will not make

the slightest difference to the numbers in use.I have thought that for years, and I think so still;the difficulty was to persuade the industry that theultra -cheap machine would not lessen the publicdemand. In the post-war years I imagine the chanceof proving my theory that price, within reason, willnot reduce the numbers of machines in service but'actually add to them will never have the opportunit'y of

1

testing. I believe that byi95o we shall see the numberof cyclists in this countryround about the fifteen millionmark, and that a biggerpercentage than is now thefact, will be riding goodclass machines. And this,despite the Purchase Tax.I am gravely doubtful ifthat impost will be cancelledright out ; it is too easy tocollect, too simple for anyChancellor of the Exchequerto forgo ; anyhow, as far asthe immediate future isconcerned. We may get areduction of the charge whenIncome Tax and such thingsas the beer tax come up forreview, but that, I think, isthe best we can hope for.We may have to pay for ourpast political sins, and thisis an easy way of collectingpayment, for it touches allroad travellers. It is unthink-able that car P.T. would becancelled or reduced inimpost without a similarrelief being given to thebicycle. One hopes theseadditional charges will makeus realise the wonderful valuewe get from the pastime,and take a little greater careof our property ; there is

plenty of room for such an improvement. Some ofmy trade friends think these additions to cycling costwill tend to make the bicycle of one type and class thecheapest. Personally, I think just the opposite, for thebrainy buyer will surely realise as never before thatthe very best bicycle must be the cheapest, pound forpound, mile fOr mile, and energy-that very personalpower-so easily saved.

Their Great OpportunityOF course, it is up to the trade to make the public

more cycling conscious. I'm sorry to use sooverworked a phrase, but, in this connection, it is sodefinitely right. The public are hopelessly ignorant ofcycling. To them it is hard work, the kind of labourto be dropped at the first opportunity to acquirepowered perambulation. The hikers sneer at thebicycle curiously enough-this geared walking withhorizons multiplied four times-the motorist scornsit, grows fat and puffy, and wonders why he feels soold at so ; and, as for the man -in -the -street, he isaltogether too superior to " straddle a bike," it mightupset the crease in his trousers. Yet, what is wrongwith cycling, whether it be for pleasure or the conveni-ence of owning your private time table ? There areso few private things you can own in these days thathe is a wise man who preserves at least one that is wellwithin the confines of his purse. Is it more manly tobe active than idle ; is activity and youth worthpreserving, is it a happiness to travel, and on your waysee, and hear and smell beauty ; is it a joy to go silentlyover our heritage-the King's Highway-sit amidthe grandeur over which we should dilate in excelsiswere it a picture ; is it a fine thing to make a holiday ofany idle hour ? If these things are true-and to me theymost assuredly are-are they worth preservation foryour use and that of all mankind ? You agree ? Yes,it would be difficult not to. That, then, is cycling asI see and enjoy it ; and so can you, for it is no patentedprocess of living, but simply a return to that love ofcountry that lives in the heart of most of us, gained bythe aid of a small miracle, that mechanical contrivancecalled a bicycle. The trade may believe in all thesethings. If they do, let them publish their gospel forthe greater happiness of all men.

Talk It Up, Write It upIM afraid my predilection for side issues has made

me stray from the main opic, but these majorsubjects, like the main roads, are so frequently lessdesirable or less interesting than the byways. We

were talking of prices, and I was trying to say thatwithin reason the figures at which the post-war hicytalewill be sold will have very little-if anything-to dowith the popularity of the pastime, or its use as aconvenient service vehicle. None of us buy bicyclesbecause they are cheap, but because we need the use ofthem. Some use them for pleasure, the majority as awork and errand hack ; but nobody buys a bicycle fora decoration, outside the museums,, and collectors ofhistoric models. Yes, the majority of us are utilitycyclists, and up to now the industry has beQn contentedthey should remain so. Of course, as these people growup and prosper, they don't keep on riding, even forconvenience. The manufacturers and the dealers, inthe main haven't, why should they expect other peopleto remain cyclists when the years of impecunity havepassed ? What an awful acceptance of the laissez faire ;what a mark of class distinction to fasten on a greatpastime ? All the fortunate and favourable things Ihave said of cycling are true, and the people who decry,the pastime do so in that hole and corner method of theclub and pub., talk that is so difficult to track downand challenge in the open columns of print or theplatform of debate. This sort of detraction has gone onfor years-ever since the advent of the cheap car-and nothing has been done about it outside the technicalpress.

Time For EnthusiasmIT is just about time we started a period of attraction- towards cycling, to write and talk about it with theconviction of enthusiasm. For thirty years or more ithas confounded its critics by its steady advance inpopularity and the numbers of its advocates ; withlittle enough aid it has become, and will remain, thegreatest travel vehicle of the country in point of numbers,and with these facts actually in being at this verymoment, what do you think the pastime could becomeif properly taken in hand and its virtues made articulateto the general public by the only people who can affordto undertake the gigantic task, and the only peoplewho would profit by the certain results-the trade ?I will leave the subject there for the moment ; but Ilove the game too well, and have taken health and joyin such full measure from its practice, that sooner orlater I am sure to enter the lists on its behalf, andcross a nib with my controversial friends.

Making Use of TimeI AM often charged with being a man of leisure-

ark I wish it were true. The fact is that I amfortunate in my home anchorage, which is on theedge of the country, and it is always beckoning me togo and look at our Warwickshire woods and the slopingfields running down to the little rivers. As a matterof fact my working hours are normal ones and myholidays-when I get them-are supposed to be threeweeks per anhum, extended just beyond the usualfortnight as a kind of reward for lengthy service. Whathappens is that I try to make full use of my free timeand never miss an opportunity of getting out, evenif it is only for a couple of evening hours ; that is theluck of the home position. not always comparablewith many of my friends. Yet I do think thousandsof people are slow in making full use of their bicyclesfor holiday purposes, even those short holidays. ofonly a few hours duration that many of us can snatch,

- if we will, in the mid -week periods. Because peopleoften see me roaming the countryside on these tripsend at week -ends, they imagine my leisure time is oflong measure, -whereas I am merely making good useof it.

A Happy Habit'PHIS sort of thing has become a habit, and a very happy

and varied one, which possibly needs some convictionto acquire, and drive to perfect. It is so very longago since I first attained it-as a result, I think, ofevening club runs in the first place-that except forthe club running suggestion I have forgotten how itoccurred. But I know it is worth preservation, andthat it has given me many golden hours of quietudeand simple joy that otherwise would have been lost.There is far more pleasure attached to the possessionof a bicycle than most people realize, and in so oftenforgetting- the bicycle they thereby neglect their ownsimple joys.

The Open Air. Theatre at Scarborough.Newcastle Bridge.

December, 1944 THE CYCLIST 21

* British Commandotroops are disembarkingfrom a landing barge.This is where the jobbegins for the equipmentcarrying bicycles-and thistoo is where Firestonetyres prove their staminain action.

1/4.t

tft

they use

Tires 41 tietyres

* Your help to meet this great demand is evenmore urgent. Tyres are now made with syntheticrubber and they must be kept properly inflated.

22 THE CYCLIST

MORE CARE AND THOROUGHNESSARE NECESSARY WHEN REPAIRING

PREPARATION

Clean tubes carefully with moistenedSulphur Stick and wipe off paste formed.

SOLUTIONING.7.):ROW4VALVICae

Spread thin smear of solution on tube and-""

. allow to become ""before fitting patch.

DUNLOP =* Equally suitable for synthetic and natural rubber tyres

PATCHES

December, 1944

Use a larger size patch than you wouldnormally use for a natural rubber tube.

ROUND OFF ENDS OF SLITS!

Before patching, prevent slitsdeveloping by rounding offends with scissors, as shown

411/310

TH HALTING HAND!

Rain or shine you can cycle in safety if you fit

F ERODOEiRt*D01

All -WeatherBRAKE BLOCKS

December, 1944 THE CYCLIST 23

CYCLORAMA' H. W. ELEY

the land ; if we are wise, we shall make themost of these good autumn days, and getin as many rides as we can.

A stop in the Rhondda Valley, above Penycraig. In the middle distance is Trealaw mountain,and to the right Craig-yr-Eos.

A " Nip -in -the -air " Ride -

T ALWAYS think that there is a peculiarjoy in cycling when the air is "nippy,"

and one feels that exercise is needed topromote the circulation, and get one warm.All very well to extol the pleasures of sum-mer riding, but there is a strong case to bemade out for winter riding, too . . . andthe other day, starting pretty early in themorning, I had a grand ride through thecountry around Tamworth, and Lichfield,and Atherstone. " Border " country this. . . for one may, in the course of quite amodest ride, touch Staffordshire, Warwick-shire, and Leicestershire ; and it is all goodriding country, with much of historicinterest and charm. But it was the tang inthe air which did me good ; I had been" chained " to a desk for more hours thanis good for one, and it was. good to breathethe exhilarating air and feel that the cob-webs of the city were being blown away.Get out on the bike while the glories ofautumn are here! That is sound advice,and-I take my own medicine!

How. Many?FROM time to time, one sees figures and

statistics' about the number of cyclistsin Great Britain . . . but the figures varyconsiderably, and I have never been at allsure that the oft -quoted figure of ten millionsis really accurate. What kind of a censushas ever been taken ? And does the figureinclude juvenile riders ? It would be inter-esting to have an accurate figure, and itshould be possible to obtain it . . but Iconfess I do not know from what source.If the total is ten millions, then the cyclistsof these islands are-or should be-a verypowerful body, with lots of " sway " inmatters of legislation affecting cycling andthose who indulge in it. .

The Lights Go Up-MOT everywhere . . . not in London ;

N but in the heart of the Midlands, thelast couple of weeks have been memorable,for streets have been gay with lights, andthere has been a new joy in taking a ride

at night. In spite of the fact that the re-stricted lighting is not, of course, anythinglike pre-war illumination, the differencefrom the true -black -out has been remarkable,and more than welcome. One may hope thatthe better lighting in Midland towns mayhave a good effect on casualty figures-stillfar too high.

Memories of MiddelburgHOLLAND is in the news, and because

in peacetime I used to visit WalcherenIsland fairly frequently, and loved thecycling Hollanders, the story of destructioncaused me to grieve. Everyone cycles inHolland, and I have good memories of ridesaround Middelburg, that quaint medievaltown ; of rides to the great wall of West-capelle ; of Flushing-where one greetedone's English friends off the boat fromHarwich. Good, flat country-ideal forcycling, and even if one did not take one'sown mount across, it was so easy to hire amachine from one of the many shops whichcatered for the cycling visitor. When Hollandis really free, and the war is ovet, I plan togo there again . . . and indulge in good rideswith friendly Dutchmen-those cheeryDutchmen with the inevitable cigars ; thosegood Dutch women, with their passion forscrubbing and cleaning, and their skill inmaking round Dutch cheeses!

Crown of the YearIT was good, indeed, during October, to

get out into the English countrysideand see the colourful pageant of Nature.The berries of the rowans gleamed likeblood -drops in the sun ; the elderberrieswere laden with black clusters of berries,and on the high ridges the trees were turn-ing to gold and russet and brown. MotherNature was mixing her autumnal colourswith a lavish hand, and in the woodlandsthere was a riot of beauty. The cottagegardens were still gay with flowers . . .

Michaelmas daisies, asters, dahlias, goldenrod . . . and in the rose beds there werestill some lovely blooms. All too soon thepicture will fade, and King Winter will grip

The Names on BikesTT was a Sunday in October, and there-1- were three of us . . . taking our rest atan inn. Our bikes were propped up againstthe trunk of an ancient elm, and we sat andsipped our ale on a weather-beaten oldbench. I fell to thinking of the names ofthe three machines. One was a " Norman " ;one a Robin Hood," and:. the third a" Three Spires." And, somehow, imagina-tion ran riot, and the names brought visionsof places, and things, and associations." Norman " . . . a bike from Ashford, inKent, and I had thoughts of the ordealwhich Kent has endured these long war.years ; I thought of great shells droppinginto Dover Town ; of all the flyffi.g-bombswhich have hit the Kentish towns so hard ;and then I thought of how Kent has everbeen in the forefront of English history . .

thoughts came to me of St. Augustine, of thePilgrim's Way, of the murder of Thomasa Becket in ancient Canterbury.

Memories of SherwoodIGLANCED at the transfer on the " Robin

Hood " machine, and I was away on amagic carpet into fair Sherwood, slippingthrough the glades with the gallant Robinhimself, talking under a huge tree with MaidMarian, and enjoying all the thrills of out-lawry in the dense forest) And when Iturned my eyes to the " Three Spires " bike,then I wandered in spirit in old Coventry,and thought of her scars, of her fascinatingindustrial history . . clock -making, silk,bicycles, ,rotor -cars, aeroplanes! I thoughtof Starley, and the old pioneering days ofthe cycle industry. And I even had a mentalpicture of Lady Godiva making her famousride through the narrow streets . . . with oldPeeping Tom taking his look at the Earl'slady! All these casual, chasing thoughtsset in motion by the transfers on threebicycles! Who can say that Romance is notever at our elbow ?-

The War . . . and RubberIWAS reminded the other day that the

defeat of Germany will not necessarilymean good or ample supplies of raw rubber.Malaya is still in the grip of the Japs, anduntil we get back that rich and chief sourceof crude rubber supplies, I guess we shallhave " synthetic " rubber with us. "Syn-thetic " has done a remarkable job, but Igather that it can never take the place of" crude "-and we .must hope for the daywhen the Malayah estates will be free again,free to send us those picturesquely -markedcases of raw rubber to feed the machines inthe tyre -making plants, and give higherquality to our cycle tyres. Meanwhile, theMinistry of Supply is still preaching " tyreeconomy " and the necessity of taking specialcare of our covers and tubes.

President of the RoadfarersTHE holder of this office, as many cyclists

know, is Lord Brabazon of Tara-theholder also of the first air -pilot's licence inGreat Britain. Keen, practical, and pos-sessed of a vast knowledge of mattersaeronautical, Lord Brabazon is interestednot only in the skies, but in our roads, andall " Roadfarers " know with what urbanityand charm he presides over the functionsof the club. -11

24 NEWNES PRACTICAL MECHANICS

St Mary if, "Viigra Ai:Idea-bury (Ome)stn3th '

Touring Costs-A RECENT paragraph was cut off in is youth

owing to my unfortunate habit] (the result ofenthusiasm I) of over-running the space allotted tothis contribution. I was pointing out that the xis. 6d.per day which had been spent on my July tour did notrepresent the actual cost of the holiday. After all-it may appear to- be regrettable I-I've got to live-somewhere-and, being away from home, the cost ofmy " keep " there was, of course, saved.

I sin now in a position to supplement these detailsby citing the experience on an October holiday. I spentfive nights at a house in Shropshire, where I paid75. 6d. for dinner, bed and breakfast : total, 41 17s. 6d.'Devoting most of the hours of daylight to cycling, Ihad five lunches at various establishments along theroad, at a total cost of i 3s. On the first day of theholiday I also had tea, which cost me is. 9d. Thusmy total expenses for those five October days (duringwhich I did 381 miles) were 12S. 3d., averaginglos. 6d. a day. And there's a war on! The total isa shade lower than normal for these particular timesbecause-reluctantly enough !-I made do with threemeals a day instead of four. With a substantial lunchat t p.m., and a good dinner at 6 or 7 p.m. I managedto live without my usual tea, except on the one daymentioned. Once again I emphasise that this half -guinea a day is the gross figure, taking no account of themoney I saved on housekeeping bills at home. I amalmost constrained to ask: " Can you beat it ? "

-And ExperiencesLET me add (though it is hardly germane to the

aspect of the matter which I set forth to discuss)that from the weather point of view the former of thesetwo holidays was the most brilliant I have everexperienced. It may also be added that, while myriding - programme was irregular (sometimes I did3o -odd miles in the morning, and sometimes only iz),there was always time for sitting on walls and gates,doing nothing vigorously, or lying full length on grassybanks. So long as I was out for iz hours or moreevery day, I didn't mind how I'spent the time, thoughit will be noted that I averaged 64 miles a day-withoutreally trying ! I was not quite so lucky with the weatheron my October holiday, having a pair of wet feet onmost of the five days.

Return to LamplightTT is always with mixed feelings that I view the

" taking off of the hour," and the inexorablebackward movement of lighting-up time. I regret thedeparture of the summer, but I welcome the arrival ofthe autumn. I deplore the shutting -down of the longevenings 'of light, but I hail the coming of ampleopportunities for riding in the dark, of which phaseof the pastime I have always been inordinately fond.I appreciate, of course, that one can have a quota ofnight -riding at any time of the year, but, in practice,one does not exchange the joys of going to bed for thedelight of cycling beyond midnight. During what wecall the winter months it is easy to indulge one's fancyin the way of riding behind a lamp, and I have neverbeen backward in obtaining my share of this fascinatingaspect of cycling.

Riding in the DarkDURING two recent week -ends, when I spent the

Saturday night away from] home, I was able to enjoya pleasant spell of riding in the dark, and I found allthe old-time joys awaiting me. 'Co some extent, thosejoys have been eclipsed by the annoying wartimeregulations relating to our lamps, but these have nowbeen very much eased, and I feel quite at home, andperfectly happy, travelling through the pool of darkness.What a pleasure and advantage it has been to get backalmost to pre-war lighting ! I don't think that thewhite matt decoration of the " innards " of a lampdetracts much from the volume of the light, and I findthat, with the disappearance of the mask from thefront glass (I ripped mine out as soon as the powers -that -be said " Go," and without waiting for the

Britain's Touring GroundsQTATISTICS have shown that among the numerous

touring grounds of the British Isles, Devon andCornwall have held a leading place in popularity formany years. There is no particular reason why thetwo counties should always be merged, as they arequite dissimilar. Perhaps, however, for hard -ridingtourists, unwilling to linger too long, there is notsufficient territory in either county to occupy themfor a whole fortnight. Without doubt there are manyof the more leisurely ones who are content to " do "Devonshire by itself and to reserve Cornwall foranother holiday. It is not too much to say that theseWill derive the greatest benefit, as many fortnightsmust elapse before one can really say that every cornerof these two paradises is familiar ground. Taking themas a group, however. what are their chief characteristics ?

Glorious Red DevonONE may say that among the English counties there

is no other that can be matched with Devonshireas an all-out playground. North, south and centre thereis unlimited beauty and unrivalled variety. Yet northis different from the south, and the centre is reallya land apart, unlike either. Most people agree thatNorth Devon is more appealing-I won't say motebeautiful because I do notprofess the ability to definethe term to everyone's satisfaction. The north ismore unspoilt, less sophisticated, but the south possessesthe colour, the sub-nemical luxuriance of foliage thatis not present in the north.At the same time the southcontains most of the popular" resorts," full of boarding-houses, parks, and an air ofartificiality that the averagetourist does.not hanker for.Here, however, particularlybetween Teignmouth andTorquay, will be found thatexquisite combination of redloamy soil and fresh green.There is perhaps 'no morecolourful stretch of coast inBritain than the Labradorslopes. On the north sidethere is one ever-changingpanorama of woodedslopes, secluded combes,deep ravines andprecipituous cliffs.

Hills and SceneryTHE roads are good in

parts, but some of thefinest scenery can be foundalong roads that deter allbut the hardy cyclist. Thegradients are severe, and it

My Point 60

of View'5

(?)Y WAY FAR E rzg

Aappointed day !), I am obtaining pretty wellall the illumination I require. My night speedhas gone up. I do not mind how --black thenight is-on the other hand, the blacker the.night, the better can my light be relied uponto " do its stuff " ; and the most tortuous andinvolved of the country \ lanbs are 'receivingquite my old-time I patronage. Incidentally,having tried most ;kinds of lighting methods,I pin my faith to carbide.

One pleasant feature of the current returnto lamplight is that the country scene is nolonger a 'mass of unrelieved black. Thecottage windows, as of old, wink

cheerfully at us as we pass, the internal lightingbeing screened by multi -coloured (or even white)blinds. Now that we are back at this halfway housebetween pre-war and post-war lighting arrangements,one realises how dismal the uniform blackness of thecountryside during the war -years really was.

Two ConversationsT HAD just started out for a day's ride the other

Sunday morning When a voice at my elbowmurmured : " Good morning, sir ! This isn't the way

December, 1944

to Ireland ! " A pretty thought, coming from a youngfriend who, has cycled far and wide on the Continent ofEurope, and who is aware of my affection for " theIsland of the Saints " ! We sped along in an easterlydirection, and then' I retorted : " If I like to make itso, this is the way to Ireland. My wife remarked tome at breakfast half -an -hour ago that any road seemsto take me to the places I desire to visit. That is thecase, and I instanced to her (as I now do to you) mymonumental ' short cut ' from Killarney to Birminghamvia Dublin, Belfast, Larne, Stranraer, Ayr, NewtonStewart, Dumfries and Carlisle. So, if that's the wayfrom Ireland, I claim that this is the way to that grandtouring country, although we're facing in the wrongdirection at the moment. . . . So long ! I'm turningright here ! "

My hostess at a tiny cottage whose windows, whenthe foliage permits, commands a view of the MalvernHills, goes by way of being a cyclist-not exactly acyclist of my calibre, for the probability is that Iaccount in a month for a greater distance than sheachieves in a year. But site is a cyclist-and she confessesshe loves her bicycle, which she uses for cons -eying heron shopping expeditions and for going to whist -drives,etc. The other Saturday, when I called at that tiny(and remote) cottage for tea, my hostess told me thatshe had just cycled to the next village, three miles -

away, oh a matter of business. Here and there shesaw a friend waiting at the roadside in the hope ofgetting a lift, and one of them called out : " Oh !Mrs. Smiler ! I wish I could cycle like you do ! "

" Hard Work" FetishT AT once took up the cue. .""They could if they" would," I opined. " But the trouble is that they won'ttry. They leap to the conclusion that cycling is hardwork : they can't see that it's really much easier than.'walking-and very much easier than standing (boutwaiting for a lift. Why the blazes "-I was warmingup !-" they won't give cycling a fair trial, that's allone asks, I can't imagine. These people would be justas enthusiastic as you are if only the desire to cyclewas there, and if only they would get rid of this hardwork fetish."

All of which I believe to be profoundly true.

Notes of a HighwaymanBy LEONARD' ELLIS

is said that there is no hillier length of road imaginablethan that from Portock to Ilfracombe, but what a wealthof 'grandeur. Inland there is Dartmoor, a wild tract ofcountry studded with isolated tors. Here in the properseason iS a purple and green world of heather andbracken. Roads are few, and there are places where it -is inadvisable to stray from the beaten tracks. Here ishistory and mystery, solitude and grandeur, peace °unequalled. &ornwall is entirely different from Devon,'

Cornish CoastlineTHE people are different, scenery is different, the -

accent is different. Another great difference is thatone must concede at once that by far the greater part oftCornwall's glory lies along the coast, and as a coastline'it has no equal. Along the south-west corner, embracingthe Lizard and Land's End, is some of the mostwonderful rock scenery that one Could imagine. "Cornwall has many other attractions, and not the least -is the wealth of memories and reminders of King Arthur,and the numerous quaint fishing villages, teeming with:interest and pictures. In neither county does industry.obtrude unduly. There are a few large towns in Devon.but apart from these almost the only " faetories " arethe little places devoted to the manufacture of the:famous Devon ware. There is more industrialism inCornwall, but even this cannot compare with mostcounties. The county has been famous for manycenturies for its tin and china clay, and the evidencesare hard to hide. Stone quarries are also encountered,but it cannot be said that smoke or ugliness predominate .

anywhere.

r-

The Lizard, Cornwall.

Whatever your age, you can nowstudy for the all-important Matric-ulation Examination at home on" NO PASS -NO FEE " terms." MATRIC " is the accepted pass-port to all careers, and opens upopportunities which would other-wise be completely closed to you.Ensure the success and security ofyou and yours through post-wardifficulties by writing for ourvaluable "Guide to Matriculation"immediately -FREE and withoutobligation. B.T.I. (Dept. 160/,356, Oxford Street, London, W.1.

AS SIMPLE TOUSE AS A FENWill etch on anymetal. Quicker thanmachine engraving.From Dealers or direct.srn.l for leaflet ' /.13."

CAN YOU PLAY THE PIANO

have you not acquired thisIf yon are a music lover, why

41' enjoyable accomplishment andgreat social asset r Doubtlessbecause the prospect of prAc-lice ! practice ! practice I hasilisfnayed and discouraged you.I have enrolled more that

15,600 adult pupils during the War.Luring 40 years I have 'taught over05,000 by post in a third the time,with a quarter the work, at a tenth theexpense of the ordinary methods ofdull, mechanical wearisome practice,AND I CAN TEACH YOU. Ordinarymusical notation only used, no freakash methods, enabling you to read andplay at sight any standard musical

composition. Send for FREEBook and advice. Say

Moderate,.

Elementaryor Beginner.

Mr BECKER (Dept. SUL 69. Fleet St., LC 4

WE WILL PURCHASEModels and Machines of everydescription. Railways andparts from gauge 00 to 15.Boilers, Engines, Boats, Mec-cano, etc., etc. State fullestparticulars and price requiredin first letter to save unneces-sary correspondence.We also have FOR SALE fairstocks of the above. Stampwith requirements.

BOTTER ILLS, Department.HIGH STREET, CANVEY, ESSEX

HAVE YOU HAD YOUR COPYIf not order it now to avoid

disappointment."AMERICAN MIDGETS"

Radios and Valves.This useful booklet describesclearly with many circuit dia-grams the peculiarities of thesmall American (Midget) setsfrom the repairer's point ofview. Valves used in theseradios are also described withbase diagrams and characteristics

PRICE 218, post freeFrom V.E.S. (P), Radio House,Melthorne Drive, Ruislip.

LARGE DEPT. FOR TECHNICAL BOORS

FOYLES* BOOKSELLERS TO THE WORLD *

New and secondhand Books onEngineering and all other subjects.

119-125, Charing X Rd., London, W.C.2Open 9 a.m.-6 p.m. including Saturday.Telephone : Gerrard 5669 (16 lines\

W & G. Foyle.

UNIVERSAL MAINS RECEIVER4 VALVE MEDIUM WAVE

You can build this set, and be the envyof your friends ! Simplicity itself..The " Wizard " gives splendid toneand volume. 5/- brims you the follow-ing : Very clear instructions, includingpoint to point wiring, with every wiredescribed. Circuit Diagrams. Full-sizeComponent Layout Drawings withalternative wiring" for 7- and 5 -pinvalves. Parts List and Prices. UsesBritish valves obtainable from us, oryour local Dealer. Components soldseparately. " WIZARD " enquiriesanswered free S.A.E. No callers.Regret Battery version delayed (postfree 30. 6(1.). Book your copy in advance.

WELDONA RADIOACCESSORIES LTD.,"WELDONA," THE AVENUE,

FINCHLEY, LONDON, N.3.

"Easily the best soldering fluidobtainable."

This statement by a regular userof " BAKER'S " expresses thegeneral opinion of motor andengineering trades. Sold in 6d.,II- and 116 tins. Also in Bulk.

SIR WM. BURNETT & CO. (CHEMICALS) LTD.Gt. West Rd.. Islewortk. Middx. Hounslow 0476

LINESIDE FEATURES :" 00 " " -

BUFFER STOPS ... 1/9 2 6 & 5'3FOGMEN'S RUTS .r. 219WEIGHBRIDGE AND

OFFICE ... 5'- & 7;6COTTAGES ... 618COAL OFFICES... ... 3/9 6:'6

Postage extra.BOOKS:

A.B.C.G.W.R. LOCOS," 1,6, by post 1 8.5" A.B.C. S.R. ELECTRICS, ' 1/-. by post 1 2.1°" OUR RAILWAY HISTORY "

Part I 3 Part II 34. Postage 3d. extra." MODERN LOCOS. & ELEC. TRACTION

OF S.R.." 1 6. Postage 3d. extra." CARDBOARD ROLLING STOCK AND

HOW TO BUILD IT," 2,6, by post 2 9.SAL DEPT.:L.M.S.. L.N.E., O.W.R. Electric Locosavailable (7 mm. only), also Wagon andSignal Parts (4 mm. and 7, mm.).TYldesley & Holbrook. 109, Deansgate,Manchester, 3. Phone: Bia 7312

IDEASWANTED

We are open to consider anyideas or patents of practicalworth, with a view to makingand marketing them. Writein confidence to :

Edron Industrial Group,7 Park Lane, London, W.I

MISCELLANEOUS

PATENTS PROMOTERS CO., [LTD.,require immediately patented inventionsfor manufacture in U.S.A.-Write CravenHouse, Kingsway, W.C.2. Tele. :HOLborn 6448.

MODEL Engineers supplies Brass andCopper Tubes, Sheet, B.A. Taps, Dies,Screws, Strip Steel, Brass and Copper,Costing Moulds for Metal Toys. 3 pageList Post Free. -W. Roberts, Engineer,Tai Bach, 1).1aenan, Llanrwst, N. Wales.

WANTED. -Unit X Machine, goodcondition. Please write Jenkins, 234,Leagrave Road, Luton, Beds.

MICROMETERS REPAIRED. Haveyour Mic Faces re -lapped as new within.00002. -Agency, 123, Station Road,West Drayton, Middlesex.

TO PATENTEES AND OTHERS:Patents and Ideas wanted for BicycleFitments and Accessories and similararticles, suitable for development and

.marketing. -Particulars to Sinith, 5,Acol Road, London. N.W.6.

NEW MACHINERY. For essentialwork only, Electric Motors, Band Saws,Drilling Machines, Pumps, Grinders,Welders, etc. -John P. Steel, Bineley,

Learn EsperantoA simple auxiliary language -easyto learn, logical, musical andpractical, and used throughout theworld. To the stay-at-home itenables pen -friends to be made inall pans of the world. To thetraveller it provides easy contactwith people of other lands. Itpaves the way to internationalfriendship.

A complete correspondencecourse costs only 5s. includingtextbook and correction ofexercises.Write for free particulars today

BRITISH ESPERANTO ASSOCIATION,IINC.Dept, P.B.S. Heronseste,,Rickmansworth,

Herts,

4 USEFUL BOOKSI. "THE ART OF SCALE MODEL

AIRCRAFT BUILDING."By V.1. G. Woodason, 4111, 816 cloth.

2. "MONEY IN EXPORTS." (Tradingin 41 different countries.) Secondedition, 1016.

3. "AROUND THE WORLD WITH"PEN AND CAMERA."

By W. Buehler.A Practical Course in Journalismand Press Photography, 319.

4. TOYS FROM SCRAP FORPLEASURE OR PROFIT. 3/6.

All Nighty commended. Sold xiar.p forfull particular,

Aircraft, Ship, etc. Models and Paintingsalso undertaken.

Stamp Collections Bought.USEFUL PUBLICATIONS,

37, ALDWYCH, LONDON, W.C.2

RATCHET & REVOLUTIONCOUNTERS

Ask forLeafletNo.18/3Speed up to6,000 r.p.m.B. & F.CARTER & COLTD., BOLTON S

" VIBRO-ARC " Engraving Pen

For rapid engraving anymetal -hard or soft.

Operates from 4-6v.Post Battery or A.C. Trans -Free former.

HOLBOROW,(38), Boroughbridge, Yorks.

Build your ownPOWER DRIVEN FRET -JIGSAWfrom easily obtainable parts andmaterials ONLY, costing approximately

55!-.Set of clear DIAGRAMS and IN-STRUCTIONS (from the actual, well

tested Model). Price 3-.This machine will cut out Animals,Dolls House furniture, Wheels. Jig -Saw Puzzles, and 101 other very sale-able articles for the Xmas Trade.Using Coping Saw (at 2d. each) will

cut stood up to 1 inch thick.P. M. BARHAM, " Hilltop." Brad -

more Green, Coulsdon. Surrey.(Parts Stocked.)

TOYS, MODELS and NOVELTIES.Send for range of popular designs withfull instructions. 2/6 only, post free. -Harrod, 10, Beaconsfield, Road, Maid-stone.

MODELS made by engineer whospecialises in all Patent Work, Design,Drawings, and marketing of patents.-BBJY, London, W.C.1.

THE WATCH FAMINE. -10 assortedwristlet out of order watches, 351- the 10.10 Pocket ditto, 30/- the 10. 6 smallSilver Pocket Watches, 25/- the 6. Handyfor unprocurable material. -Me rkeJeweller, Pilgrim Street, Newcastle -on -Tyne.

12in. POWER BENCH BANDSAWS.Make your own, send 10/6 for workingprints and photograph. Sound. simpledesign.-Rawlinson (PM), 34, CaegwynRoad, Whitchurch, Cardiff.

A FEW Sets of 12 Rotary Files orHandmilling Cutters. Slightly used.Good make. 7s. 6d. per set. Bargain.Also odd Reamers and Lathe Tools. -Write T. R. Cave, 16, Otter Street, Derby.

ELECTRIC ENGRAVERS. -Powerfulinstruments in cylindrical Case,- onstand with spring attachment andswitch. Suitable for dog collars, toolmarking, etc., 4-6 volt model, price550- ; A.C. Mains model, 200-240 volts,75/-, postage 1/--8:ATTER)/ CHARGERS FOR A.C.MAINS. FOR CHARGING 2 -voltaccumulators at I amp. Parts withdiagram, 1213. Complete, 21:6. Postage10d. Delivery 10 days from order.FOR TRICKLE CHARGING CARCELLS, parts with diagram. Output1.4 amps. for 6v. cells, 30:- set. For12v. cells, 35;- set. Delivery as above.MICROPHONE. BUTTONS. 2,3.TELEPHONE W'ATC-11 RECEIVERS,9/6 each.INSTRUCTIVE CHEMICAL SETS.No. L ,Set containing 18 chemicals,apparatus and instruction book. Price18/6. Post 8d. No. 2 Set containing

_16 chemicals, apparatus and book.Price 1I,6. Post 8d. No. 3 Set' with9 chemicals, apparatus and book.Price 6,, Post 7d.

'CYCLE HEAD LAMPS, completewith battery and bulb, 4 9. Post 7d.

ECONOMICELECTRIC CO.,64. London Road, Twickenham,

Middlesex.Tel.: POPesgrove 1318.

KIRK DESIGNS LTD.

WOODFORD GREEN, ESSEXTel: Buck hursi 3835

BLUE PRINTS OF YACHTSFull Size Details available ofModel Sailing Yachts, from

316 to 71-.Please send 6d. P.O. and S.A.E.for List and Sample Print of

Sail Plan of One Yacht.Many of the Yachts are equip-ped with automatic steering

(full details).

r. 11,non.

Easily madeFrom Our

Castings.

J.HALLAM& SON,

Upton, Poole,Dorset.

MINIATURE PETROL ENGINES farAeroplanes and Speed Boats.

SILVER PLATING SETSas supplied to Electroplaters, but inminiature, for small parts, etc., instruc-tive small sets, 191- inc. post. Send28d. stamps for printed folder.MERCURY & PLATINUM SCRAPrequired, high prices paid, please writefor offer, or send (not under 2 pounds

Mercury purchased).ARGENTA PRODUCTS (D. C.),-40, Harrogate Road. LONDON, E.9.

L. ORMOND SPARKSCONSTRUCTORS' DATA SHEETS

These Data Sheets provide full con-structional details, together with fineblueprints, of tested and guaranteeddesigns, specially prepared to meet,theneeds of the amateur and existingconditions.ELECTRIC GUITAR UNITS.-Coe-vert your guitar to an Electric model.Fu jj details covering principle, opera -ti c% and construction of three electro-magnetic units. PriceELECTRONIC ONE - STRINGFIDDLE. -This is distinctly noveland must not be compared with theold-fashioned instrument. Its richquality and tone provides unlimitedscope. Price 3'6.TRANSVERSE CURRENT " MIKE."-Simple to make and ideal for speechor music. Price 28.INDUCTION or SHOCKING COIL. -A piece of apparatus, easy to make,which is interesting, amusing andbeneficial. Price 2/8.31 WATT A.C. AMPLIFIER. -Aquality amplifier, ideal for use withgramo pick-up, etc., fitted with volumeand tone controls. Price 2, 6.TWO -VALVE AMPLIFIER (Battery).-Fine volume and tone. Volume andtone controls fitted. Automatic bias.Price 2/6.L.T. CHARGER. -This design is forA.C. mains, and covers a 2 -volt TrickleCharger and one suitable for 6 -voltcells. Price 2'6.Other Sheets available and in course ofpreparation. Stamp for list.

L. ORMOND SPARES 0/09. Phoebeth Road, Brockley, S.E.4

it%

One of the following Courses taken at home in yourspare time can definitely be the means of securingsubstantial promotion in your present calling, or entryinto a more congenial career with better prospects.

ENGINEERING, AERO, ETC.Radio-Aero Engines-Aero Navigation-AircraftDesign-Welding-Aerodynamics-Electrical Engin-eering-Television-Electric Wiring-Talking PictureWork-Generation and Supply-Works Management-Metallurgy-Refrigeration-Planning, Estimating,Rate-fixing-Time and Motion Study-Aero, Inspec-tion-Automobite Engineering-Sheet-metal Work-Engineering Draughtsmansh,ip=Aero Draughtsmin-ship-Jig and Tool Draughtsmanship-Preis Tool andDie Draughtsmanship-Structural or RIF ConcreteOraughtsmanship Sanitary Engineering R.A.F.AND R.N. PILOTS AND OBSERVERS.

GENERALMatriculation-College of Preceptors-CharteredInstitute of Secretaries-Aircraft Apprentice-Emergency Commissions (Army).

MUNICIPAL SERVICE,,,School Attendance Officer-Handicraft Teacher-Registrar-Rel ieving Officer-Sanitary Inspector-Weights and Measures Inspector-Inst. of Mun.and Cy. Engineers-P.A.S.I.

THE BUILDING BOOM-SECURE YOUR SHARE !

The Free Guide also gives particulars of ourextensive range of modern Building and StructuralCourses, Building Draughtsmanship, etc. Thegreat post-war Building programme offers un-limited prospects to technically trained men.

-,--BECOME A DRAUGHTSMANor AERO INSPECTORAND EARN BIG MONEY

Men and Youths urgently wanted for reservedoccupations as Draughtsmen, Inspectors, etc.,in Aero, Jig and Tool, Press Tool, Electrical,Mechanical and other Branches of Engineering.Practical experience is unnecessary for thosewho are willing to learn-our Guaranteed

" Home Study " courses4VP

will get you in.. Thosealready engaged in theGeneral Drawing Officeshould study somespecialised Branch suchas Jig and Tool or Press .Tool Work. and so con-siderably increase theirscope and earningcapacity.

NATIONAL INSTITUTE_ OF ENGINEERING

148, HOLBORN,(P 'LONDON, E.C.I

NEARLY SIXTY YEARS OFCONTINUOUS SUCCESS

SOUTH AFRICAN BRANCH : E.C.S.A. P.O. BOX 8417 JOHANNESBURG.

"PRACTICAL ENGINEERING" said-We recommend all readers interested in improving their position

to apply for a copy of this valuable Book. " Success inEngineering" is not a pamphlet. It is a 124 -page book,containing valuable and vital information on all branches ofengineering . . . There are many engaged in engineering whoowe their success to The National' Inititute of Engineering.The FREE GUIDE explains':

Openings, prospects, salaries, etc., in Draughts-manship, Inspection, and opportunities in all otherbranches of Engineeting and Building.

How to obtain money -making technical qualificationsthrough special RAPID FULLY -GUARANTEEDCOURSES:

Write now for yourcopy, of this remarkablepublication.A.M.I.E.E., A.M.I.Mech.E.,A.M.Brit.I.R.E., A.M.I.P.E.,A.M.I.C.E., A.M.I.Struct.E.,A.M.I.A.E., A.F.R.Ae.S.,

M.I.S.E M.R.San.l.,London B.Sc., Degrees.Fully gruaranteed postal courses forall the above and many otherexaminations. Fully described inthe Free Guide.

THE ACID TEST OF TUTORIAL EFFICIENCY +.SUCCESS --OR NO FEE

FOUNLDED 1885 FOREMOST TODAY - OYER 100,000 SUCCESSES

1" Practical Mechanics" Advice Bureau COUPONi Thi., coupon n. available until Detember30th:,1944, and

must be attaated to all letterscontainingqueriea,"togetherGth 3 penny Aaiune. A saaapeal, adolie8sed . envelope

,004 also be anol000d. .,-;:,- -v .:"'Practical Mechanics. .-- Deseinber; 1944.

We definitely.guarantee that if you fail to pass the examination forwhich you are preparing under our guidance, or if you are notsatisfied in every way with our tutorial service-then your TuitionFee will be returned in full and without question. This is surelythe acid test of tutorial efficiency.

If you have ambition you must investigate the Tutorialand Employment services we are able to offer: Foundedin 1885, our success record is unapproachable.

Why not fill in and post the attached coupon NOW for furtherdetails and Free .Authoritative Guide to openings in Engineeringand Building? This book contains a mine of valuable and exclusiveinformation and may well prove to be the turning point inyour career.

PROMPT TUTORIAL SERVICE GUARANTEED.

FREE COUPON 1

To NATIONAL INSTITUTE OF ENGINEERING(Dept. 29), 148, Holborn, London, E.C.1.

Please forward your FREE Guide toNAMEADDRESS

My general interest is in : (i) ENGINEERING (Place a doss against(2) AERO (3) RADIO (4) BUILDING the branches in talc k

(5) MUNICIPAL WORK you are interested.)

The Subjeceor examination in which I am especially interested is

To be filled in where you already have a special preference.(Id. stamp only required if unsealid envelope used.)

Published about the 30th of each month by GEORGE NEWEL'S. LIMITED, Tower House, Southampton Street, Strand, London: W.C.2, and Printedla England by the Newnes and Pearson Printing Co.. Ltd., Exmoor Street, London, W.10. Sole Agents for Australia and New Zealand -C 'ou A Gott+,Ltd. Sole agenta for South Africa-Central News Agency, Ltd. Subscription Rates (including postage). Inland -bits. Id. per annum. Abu ION. For

annum. Canada, 10a. per annum, Registered at the G.P.O. for trananniaston by Canadian Magazine Mt.