FIRING THE GUNS - 2

Palmerston Forts Society The Redan

No. 34 June 1995 5

base horizontal position finder, but Ihave not yet come across references toit. The late Victorian instruments weredesignated by letter and mark. i.e.‘D Mark I’ More of this in the next arti-cle when I shall attempt to explainhow the instruments worked in moredetail.

The invention and development ofthese complicated range and positionfinders can be attributed to one man, aMajor Watkin. Consequently they wereoften known as Watkin Range or Posi-tion Finders.

At first I assumed that the two types offinder differed in that the range finderscould calculate only range whilst theposition finders were able to calculaterange and position. But I have sincecome to the conclusion that depressionrange finders were also capable ofdetermining position. They differedonly in the way that they did it. The1915 manual of Coast Defence RangeFinding explains that the range finderwas able to determine the distanceand training of the target from itselfwhilst the position finder could deter-mine the distance and direction to thetarget and in addition the position ofthe object could be plotted by theinstrument on a correctly orientedchart so that range and training fromany other site marked on the chartcould therefore be planned. The posi-tion finders had a chart table beneaththe sighting telescope and this wasmounted on three pillars, often of con-crete, in a position finding cell.

The first range finders

The first Watkin range finders werefitted to tripods. The Officer Command-ing Royal Artillery Sheerness 2/10/86pointed out that it would desirable tomount the Watkin depression rangefinder in a permanent position insteadof on its tripod. On 18/10/86 MajorWatkin concurred. The Director of Artil-

Having visited many of our remainingVictorian coast defence forts and bat-teries I was fascinated by the nowempty position finding cells that litterthem. My researches into the instru-ments that were sited within theseenigmatic chambers has led me alongmany blind alleys. It seems that noone has published a definitive historyof the subject. Whilst I do not presumeto claim that I know all there is toknow about the different types ofrange and position finder in use duringthe late Victorian period I can at leaststate that I have gone some way tounravelling the problem. The differ-ence between a Depression PositionFinder and a Depression Range Finderand that between an Electric PositionFinder and a Horizontal Position Findermay be more difficult than I have sofar determined. To add to the confusionoriginal documents also label someinstruments as Depression HorizontalReceivers, and Horizontal Transmittersor just plain Position Finders. If anyonecan provide any more information Iwill be happy to publish it. MeanwhileI have attempted to unravel some ofthe mysteries and may have got itwrong in the process. Here goes.

The main instruments used to calcu-late range and position in coastbatteries during the later Victorianperiod were the range finder and theposition finder. The range finder in usewas known as the Depression RangeFinder or. D.R.F. whilst the positionfinder came in two varieties, theDepression Position Finder, D.P.F. andthe Horizontal Position Finder or H.P.F.To further complicate matters therewere different types of horizontal posi-tion finder depending on the length ofthe base, viz the ‘Short Base Observa-tion Station Position Finder’ or S.B.P.F.(Two of these were fitted to FortGilkicker in the 1890s These will bedescribed in the next article). Presum-ably there was a corresponding long

FIRING THE GUNS - 2 Watkin Depression Position Finders David Moore

lery 6/12/86 directed the OfficerCommanding Royal Artillery to for-ward the instrument to Major Watkinin order that a suitable fitting could bemade. The instrument was forwardedand required a slight alteration whichwas carried out.

At the suggestion of Officer Command-ing Royal Artillery Isle of Wight, theDirector of Artillery 31/03/87 requestedthe Officer Commanding Royal Engin-eers to erect concrete pillars fordepression range finders. Major Watkin25/3/87 proposed the dimensions. TheOfficer Commanding Royal Artilleryand Officer Commanding Royal Engin-eers Isle of Wight 29/4/87 consideredthe proposed dimensions too slight. TheCommanding Engineer suggested thatthe pillars be embedded in the face ofthe parapets. The cost for 10 be about£12 10s which were to come into theRoyal Engineer incidental expenses.

The Redan Palmerston Forts Society

6 No.34 June 1995

D.R.F. emplacements

The emplacement for the depressionrange finder consisted of a pit 6 feet indiameter in which was built a concreteor brick pillar, 4 feet 4 inches high, 1foot across and projecting two feetfrom the side of the pit. On the top ofthis pillar was fixed a small brassstand to take the levelling screws ofthe instrument. The ranges were trans-mitted to the gun electrically. One ormore datum points were required forthe D.R.F. as well as for the positionfinder. This was to allow the instrumentto be adjusted for height above thewater level. The datum could be theend of a pier, a rock, or any similarobject always surrounded by water,although by 1914 special floatingbuoys were often used. The bestdistance was regarded as about a mileoff to give a long base but still be seeneasily. Where the tide is small onedatum point visible from eachinstrument was sufficient to check it

RangefinderDepression

Mark II*


No. 34 June 1995 7

had been tried by the Range FindingCommittee at Fort Picklecombe inJanuary of that year. The details of theinstrument were kept secret, for fear ofits benefits falling into the hands of theenemy which it was intended to helpguard against. There were two naturesof position finder: the ‘Depression’ andthe Horizontal’. The depression positionfinder was based on the earlier depres-sion range finder and in some casesthe terminology can become confused.The horizontal position finder was laterreferred to as the Electric Position finderin some official documents, presum-able because it transmitted its data tothe guns electrically.

Using the Depression Position Finder

With the depression position finder, thetelescope was pivoted vertically andhorizontally, so that it could bedirected on to the water anywherewithin the field of view from the cell. Asimple but ingenious electrical device,the ‘horizontal attachment’, allowed thedirecting of this instrument onto thewaterline of any floating object toindicate on a couple of dials placedinside a recess close to the gun, therange and training to be given to thegun, which would result in the targetbeing hit by the projectile fired at thatinstant.

but if the rise of the tidewas considerable eachinstrument needed to seetwo datum points, one oneach flank, to allow theinstrument to be set dur-ing action if necessary.From this I assume thatthe D.R.F. read the stateof the tide by directingthe telescope of theinstrument on the waterlevel surrounding aknown datum pointrather than it beingadjusted using tidetables.

D.R.F.s issued

By the late 1890sdepression range findershad been issued in greatnum-bers. They were supplied tobatteries where there was a height ofat least 25 feet in their immediateneighbourhood. The D.R.F. could takethe place of the position finder, shouldit be be put out of action or get out oforder. In choos-ing sites for italternative positions were selected onboth flanks of the battery so as toavoid the effect of smoke. A fair field ofview was neces-sary with as muchsecurity as possible.By 1899 the following types of depres-sion range finders were fitted to manycoast batteries -

for batteriesMarkI 85 to 190 feetMarkI A 60 to 110 feetMarkI B 110 to 240 feetMarkI C 240 to 590 feetMarkI D* 30 to 60 feetSpecial at other heights

*This instrument has a screw anddrum arrangement different from thatof other marks. Specials were issued toCoalhouse Fort and Needles Battery.

Position Finders

Major Watkin had first proposed thedepression position finder for elevatedbatteries in October 1879 to take placethe place of the Position Finder which

HorizontalPositionFinderTransmitterMark II (forinstructionalpurposes)

A similar result could be obtained withthe receiving instrument of the horizon-tal position finder, where two observa-tions were combined, if bothinstruments were directed upon thesame part of the ship. By merelyobserving the ship the gun could bedirected upon it.

Determining the range and position

In the case of a moving ship, the gunneeded to strike in advance of it. Todetermine where to direct the fire of thegun a pencil was attached to receiv-ing instrument or to the depressionrange finding instrument. This wasused to plot the movement of the shipas the telescope was tracked across thechart, or plotting table, following theship. A prediction could then be madeas to the future position of the target ata selected time corresponding to thetime of the projectile's flight. The dataon the future position of the ship wasthen relayed electrically to the gunemplacement, where it was displayedon the gun dials.. The gun layer would


8 No.34 June 1995

lay his gun on the spot that the targetwould occupy in, say, half a minute bythe use of graduated scales for lineand for elevation. The gun captainthen signalled ‘ready’ to the observerwho would fire the gun at the exactmoment calculated to bring the shelland ship to the same place at thesame time.

Horizontal Position finder

The horizontal position finder used twotelescopes. One was sited some dis-tance away from the gun position andacted as a transmitting cell. The other,or receiving cell was sited close to theguns, but not so close that its observerwas obstructed by the smoke from thefiring of the guns. Both the transmittingcell and receiving cell were visiblefrom each other. The receiving instru-ment was similar in pattern to thedepression instrument, and if it wasplaced at a significant height abovethe water, could, with advantage,actually be a depression range finder.The transmitting instrument consisted

PositionFinder G


No. 34 June 1995 9

cally by the instrument. In later Marks,certainly by the early 1900s it was alldone with mirrors! The observers at thetransmitter and receiver each follow-ing the target, the receiving instrumentmaking necessary adjustments tocoordiate the two instruments whichwere connected electrically.

The difficulty lay in converting thisrange and direction as found at theobserving station, horizontal or depres-sion, instantaneously into correspond-ing figures for the gun, which mayhave been some distance off, and theequally instantaneous communicationof these figures to the gun detachmentfor immediate use. Any delay if for-warding the information would clearlyresult in the guns missing their target.

of little more than a telescope and didnot need a chart table attached. Thedistance between the two instrumentswas known and formed the base of thetriangle, the target being at the apex.In certain situations it was advisable tohave a depression instrument at thetransmitting end as well as at thereceiving end, and sometimes a singlereceiving instrument was combinedwith two transmitting ones with baselengths in different directions.

The target was observed through thetelescopes of both instruments and thebearing of the target from the trans-mitting instrument was relayed byelectrical means to the dials of thereceiving instrument. Here both thebearings were known and the range ofthe target was calculated automati-

Transmittingcell

Receivingcell

Target

base b

angle t angle r

d1d2

angle s

The Horizontal Position FinderThe range of the target is calculated byeach instrument measuring the angle tothe target respective to the base line,which is of known length. The receivinginstrument measures angle r. Thetransmitting instrument measures angle tand sends it to the receiving instrumentelectrically, to be displayed on a dial,where both angles are used to determinethe position and range of the target usinga mechanical means. I assume that evenin the earlier instruments all of thecalculations were peformed without theneed for the formula to be calculatedmentally. s = 180-(r+t) - angles of a triangle

d1 = b - sine rulesin t sin s

d1 = b x sin t sin sIn the later instruments both observersmerely followed the target with theirinstruments and the neccesary range anddirection was automatically relayed to thegun dials.

Using the chart beneath the receivinginstrument the course of the target ship isobserved and the position that it is likelyto be at in the immediate future is

Watkin prepares for the trial

Between the year 1879 and 1887 theWatkin depression position finder wasput to trial at Plymouth. On 30/4/84The Officer Commanding Royal Artil-lery Western District requested thatinstructions be given to have the posi-tion finders at forts Bovisand andPicklecombe put in working order bythe end of May for the instruction ofRoyal, Militia and Volunteer Artillery.Major Watkin RA on the 11/05/84being called upon by Director of Artil-lery on the 6/5/84 for the report saidthat Fort Picklecombe was at presentfitted with electric position finders butwas to be worked by depressionsystem but that the instruments whichwere on loan from Commissary Gen-eral were returned to store in 1879. Hecould not say how long it would taketo put the fort in working order. Asregards Fort Bovisand he said theobserving stations were finished, thewires connecting them with the bat-teries laid and also those from centralstation to centre of group. The positionsfinders were ready but required fixingin position. The range cards wereworked out and the training arcs of theguns laid but they required examina-tion to see if they agreed. Shunts andtransmitters which had been providedrequired to be adjusted and set up inposition. Electric batteries wererequired to work the dials and Morserecorders obtained on loan or demand.He could not say how long this wouldtake. On 27/05/84 the Director of Artil-lery directed Major Watkin to proceedto Plymouth.

The D.P.F. described

The depression position finder con-sisted of a telescope which wasmounted on a pedestal so that theoperator could see his target directlythrough the telescope. The pedestal,and therefore the instrument, was fixedin position at a known height abovethe waterline. The range of the targetwas determined by measuring theangle of depression of the target fromthe instrument, the base of the triangleto be solved being the height of theinstrument above the water. The direc-


10 No.34 June 1995

tion of the target was observed byfixing the telescope above a planetable, the angle of line being readdirectly as the target moved and wastracked by the observer lookingthrough the telescope.

The whole apparatus worked perfectlywhen trialled at Plymouth, NCOs work-ing the position finders with eminentsuccess. Lewis writes, It was a prettysight to watch the shot from a group offour guns fired together curving downtowards the target, and striking thewater close to it. This basic method ofpredicting was to remain in use, withminor variations, for the rest of the timethat coast artillery was in use, i.e up to1956.

The principle of the depression rangefinder was later applied to a gun sightfor shorter range weapons. This‘autosight’ as it was known, was usedby the gun layer to direct his projectileat a ship by following the bow wave ofthe target with the sight telescope, thegun being given the correct elevationto hit the target automatically. Thisalso remained in service up to 1956.

The 1887 Plymouth trials

One of the trials at Plymouth in 1887included the successful firing of theguns of the Breakwater Fort using posi-tion finders more than a mile away onStaddon Heights. This demonstrationproved that placing the positionfinders some distance away from theguns, while not ideal, did not presentinsuperable problems. The Instrumentused was fixed to a plotting table fourfeet long and 2 feet 3 inches wide;about the size of a large drawingboard. It was placed in a small build-ing or cell partly sunk, in the ground,and having a long low opening infront to allow the observer’s telescopeto cover the whole of the water in frontof the gun it served. The roof of the cellwas covered with earth to give it pro-tection and to allow it to blend into thehill on which it was constructed. Thecell for the guns at Bovisand, close by,was 250 feet above sea level, whilstthat for the Breakwater Fort was 350


No. 34 June 1995 11

of the triangle, for a range of 10,000yards, was not to be below 1,200 yards.the receiving cells were to be placedwithin 500 yards from their groups ofguns. Several cells together formed astation.

The gun battery

In the gun battery the fittingsassociated with the position finders arethe electric batteries, which could besited almost anywhere handy; thefiring plug, about 6 inches square,which took the end of the flexible insu-lated wires leading to the electric tubefor firing the gun, and which must benear to the gun; and the dials andfiring key. The key is best sited in arecess 2 feet 3 inches long by 1 foot 4inches wide by 8 inches deep, andneeded to be placed so that a mancould read the dials and give the wordof command to the gun at the sametime. In 1887 this arrangement wasunder trial and may have beenaltered.

P.F. Cells

Position finding cells needed to beconcealed from an enemy's view forreasons of safety and careful position-ing had to take account of localsurroundings. The choice of positionsfor siting a position finder were fewbecause of the need for a good field ofview. The arc of view of the instrumenthad to cover the arc of fire of the gun itserved up to its extreme range. Nocompromise could be made. The FireCommander needed to be placedwhere he could watch the action andgive directions to the observers, as wellas communicate with the Battery Com-manders by telephone. This was oftena building of similar pattern to thosefor observing with additional accom-modation for telephonists and order-lies. The position finders were con-nected to the gun battery by electriccable. This consisted of seven wires foreach instrument in order to work thedials, the firing and the signals in con-nection with this. Telephone wires werein addition. Two instrument wires andtwo telephone wires were used to con-nect the transmitting and receiving

feet. Each instrument was to give therange from a single point and thereforeserved a single gun, unless two ormore guns were close enough togetherthat their shot would strike a shipwhen they all fired in parallel over thesame water. This was the case with theguns in Fort Bovisand which weregrouped in fours. Those in the Break-water Fort were worked singly as theyhad widely divergent arcs of fire. Bythis time it was common for singleguns to form a ‘group’.

Plymouth instruments

The instruments at Plymouth were ableto read a maximum range of about5,000 yards. The latest service patternwas capable of reading ranges of7,000, 12,000 and 14,000 yards from theinstrument, the arc of fire of the gunsfalling within this range. The smallerservice pattern used was sufficient forthe older M.L. guns which were thenmounted. The cell to accommodatethem was 9ft. long by 8ft. 6-incheswide in internal dimensions.

The cells for the larger pattern instru-ments were a little bigger allowing twoobservers, which was always conveni-ent and sometimes necessary. The topof the roof was three feet above theaxis of the telescope of the instrument.The maximum arc of view was 180degrees. As much light as possible wasadmitted. The cells should be 50ft.apart but circumstances such as thoseat Plymouth, made it necessary forthem to be closer, even touching.

A row of five cells was constructed sideby side on Staddon Heights, steppeddown the hill, with a communicatingpassage to the rear.

Siting the instruments

Finders using the depression systemwere to be sited as high as possible, upto 800ft. which was considered highenough. A site as low 25ft would givegood enough results for ranges of up to2,000 yards if close enough to the guns.In a horizontal system the effectivebase, the perpendicular distance fromone end of the base to the opposite side

stations of a horizontal base positionfinder. On land the cable was laid in atrench at least three feet deep, more inexposed situations. Special attentionwas paid to bringing the cables intothe battery by a secure route. In FortBovisand they were run down themagazine passage and routed up theammunition lifts. The Fire Comanderalso was equipped with a specialmark of position finder, which differedfrom the other marks in that it was notconnected to the guns electrically.

Gun arcs and pointers

In order to give the gun the rangesignalled on the dial, an arc and poin-ter was attached to the gun near thebreech, the arc being graduated inyards, calculated specially for theheight of that particular gun abovemean tide. Various forms of arc andpointer were used and in some cases aclinometer was attached to the trun-nions. The training was given bymeans of a pointer attached to the gunand a training arc let into the floor,graduated in degrees and quarterdegrees. (A quarter of a degree wouldmake a difference of 4.4 yards at 1,000yards range) The arcs were fixed to thefloor by means of screws set in smallblocks. The Royal Engineers wereresponsible for these fittings and agreat deal of trouble was experiencedwith fitting them accurately. As someof the old platforms did not fit the racertoo well, the guns tended to go askewas they were run around for line, giv-ing erroneous readings. In these casesan average of several readings wastaken. The later platforms proved to bemore accurate fits. The zero line of thetraining arcs in all new works was truenorth; that is any gun laid true northshould have had its pointer at zero,and any two guns whose pointers wereat the same degree should have beenparallel. Every battery needed to laydown a meridian line, and to takebearings on prominent distant objectswhich were within the arcs of trainingof the guns. The number of the gradua-tion at some points in each trainingarcs could thus be determined and thearcs fixed accordingly.


12 No.34 June 1995

Programme of the 1885 Plymouth trialsOn 21st. and 22nd. October 1885 thetrials of the Watkin Depression Positionfinder took place at Bovisand Fort. Itspurpose was to meet the requirementsof elevated batteries the height abovethe waterline being taken as the basefrom which the ranges were obtainedinstead of a long horizontal base withan observing station at each end. Thenecessity for the two observing stationsand communication between themand between them and the batterywas thus obviated, and the operationof position finding much simplified.The instruments consisted of one Posi-tion Finder connected up with twodials, one of which was in the observ-ing station, and one in the casemate ina convenient position for working agroup of two guns. Arrangements weremade for both electric firing and firingby word of command. Two targetswere moored at ranges of 2,000 and3,500 yards respectively and a targetof special construction was providedwhich was towed across the range bya steam launch. The programme to befollowed consisted of1. A test of accuracy of the instrument

by observing the two targets andany fixed objects of which the exactrange was known.

2. Manning the guns and by means ofthe instrument, following the towedtarget, firing by word of commandand electricity as if in action, butlooking over the sights in order tocheck the results.

3. Repeating 2 laying on two or morevessels manoeuvring in front of thebattery; changing from one to theother and noting the time taken topick up the fresh vessel.

a) As with two observers, an officerpointing out the ship to beengaged.

b) As with one observer and a com-manding officer's lookout, a vesselbeing picked out by the latter andits position, indicated by bearingand range, communicated to theobserver; the time of the variousoperations to be carefully noted.


No. 34 June 1995 13

were always directed to the left of theobject. There was also a discrepancybetween the graduations on thetangent scale and the cardboard slipattached to the arc amounting to 100yards in one gun and 150 in the other.With practice and more accurate drillit was considered that this class offiring might be fairly successful but it isby no means easy for the officer incharge of group to lay his gunssufficiently ahead of the moving objectto compensate for the time taken to laymake ready and fire, and also to cor-rect for time of flight and drift. Electricfiring with tubes only was next triedthe guns being as before, but fired fromthe observing station on receipt of theready signal. This was not satisfactoryas by the time the guns had be laidand the signal ready appeared in theobserving station the ship hadchanged her position, and the pro-jectile would have fallen astern. It wasmoreover impossible for anything likean accurate allowance to be made bythe officer working the instrument orthe officer commanding the group. Itwas noted that in estimating the num-ber of dials required in a fort oneshould be provided for every two gunsit being extremely difficult to giveintelligible orders to more than thatnumber.

Predicted electric firing was then triedwith excellent results, the guns in eachinstance being so laid that the sightwere actually directed on the bows ofthe target vessel at the moment offiring. neither of the series in para III ofthe programme was carried out asthere was evidently no difficultywhatever in picking out any particu-lar and laying the guns of the groupon it.

Recommendations

Following the trials at Bovisand FortPlymouth the Special Committee onRange Finding made recommenda-tions as follows :-1. The trials have clearly demonstrated

the absolute necessity for somesystem for position finding. I am ofthe opinion that the results obtained

For the firing trial the projectiles usedwere studded common shell, mark IIwith gas checks, plugged usingcharges, full, 70lb P. Firing at thetowed target usinga) Service laying - 5 roundsb) Using position-finder, firing by word

of command - 5 roundsc) Using position-finder, No.1 looking

over sights and firing by word ofcommand - 5 rounds.

d) Using position-finder, electric firingfrom observing station - 5 rounds

e) Spare rounds to be expended assettled by Committee on the spot -10 rounds.

Careful note was to be taken of thetrial of the comparative advantages ofthe various methods of carrying out thepractice, speed, simplicity, immunityfrom chances of accident and accu-racy obtained. The effects of concus-sion on the instruments was also to becarefully noted.

Results of the trial at Bovisand Fort

The range on the second day was sohopelessly blocked by sailing craft thatthree rounds per gun only were fired.

First day. The ranges of various objectswere taken with satisfactory results. asit was found difficult to make accuratenotes of four guns in a group the centrepair were used for carrying out theprogram, but detachments were drilledand projectiles brought up &co at oneof the flank guns during the first daysexperiments in order that there mightbe the same amount of noise as if allthe guns were in action. The guns werethen laid on HMS Harpy, whichsteamed two and fro across in front ofthe battery. The words ‘ready’ and ‘fire’being given by the officer in charge ofthe group who also read to thenumbers 1 the changes in line andelevation as they appeared on thedial. Drill tubes only were used and anofficer looked over the sights at themoment of firing. The results were onthe whole satisfactory but from a slightwant of adjustment which was recti-fied before the next day's experimentsthe guns in this and the next series

were eminently satisfactory takinginto consideration the the want ofexperience of both officers and menand the limited time available forpreparations and preliminary prac-tice. Not only is the systemespecially valuable in casematedbatteries mounting many guns as inthe case of Bovisand but as a meansof concentrating isolated guns onany particular ship at the will of acommanding officer in a centralstation it will also meet therequirements of more modern arma-ments and increase to a verysensible degree the effective fire of afortress. I therefore recommend theadoption of the Depression PositionFinding system proposed by MajorWatkin.

2. Some minor modifications have beenproposed since the experiments byMajor Watkin and Captain GoldenRA which will simplify theconstruction and working of theinstruments and which consist in thecombination of the position finderwith the dial in the observing stationand in a reduction in size of thedials. The first alteration obviates thenecessity for two observers and thesecond lessens the risk of injury tothe dial while diminishing its costs.These modifications will necessitatea further trial before and order canbe given for the supply ofinstruments but need not delay thegeneral preparation to be proceededwith for the adoption of the system atFort Bovisand, where electricalcommunications and observingstations may be prepared at once.

3. The other sea defences should besimilarly be prepared in order oftheir importance or convenience.

Brigadier Hogg in ‘Artillery its Origin,Heyday and Decline’ cites a story thatWatkin was instructed to attend aspecial course for officers undergoingtraining in the use of the depressionrange finder. He failed. Hogg believedthe story to be a hoax as Watkinbecame Chief Inspector of PositionFinding on 1st. April 1896. In fact Wat-kin was himself responsible for the


14 No.34 June 1995

training. The Special Committee onRange Finding had recommended theadoption of his system and as soon asit was completed in one battery allofficers in the district were to beinstructed in its use.

4. It is further necessary that as soon asone battery is completed a largenumber of, if not all, the officers inthe district should be fully instructedin the use of the instru-ment. For thispurpose it is recom-mended thatMajor Watkin's services should besecured for at least three years. Hewill also at times require theassistance of a good electrician likeCaptain Holden RA andarrangements should be made tosecure this offi-cers attendancewhere necessary.

Watkin, posted

Major Watkin was posted to theDepartment on 01/04/86. The Directorof Artillery on 13/1/87 directed thesealing of the pattern of ‘Mark IaRange Finder, Watkin, with case andtripod stand’.

Watkin D.P.F.s adopted

In 1887 following more trials atPlymouth the Watkin depression posi-tion finder passed its final trials withgreat success and although it under-went several changes and modifi-cations no time was wasted inapplying its use generally to coastdefences. Lewis described the inven-tion as :-

the most important adjunct to coastbatteries yet invented, and onewhich without any exaggerationmultiplies several times the value ofany gun to which it is applied. Itwas, he said, an instrument bywhich a gun can be directed withthe greatest precision on to a spot atwhich it should be fired in order tostrike a vessel, even if the latter bein rapid motion, and which pro-vides for its being discharged at theright moment.


No. 34 June 1995 15

and Bermuda to the lists of stations towhich Depression Position findersshould be supplied.

5 to Cork5 to Aden8 to Bermuda

An 1886 report on the defences ofMalta found that choices of sites for theD.P.F. were limited. For Sliema andCambridge batteries the only possiblepositions appeared to be the flat roofsof the houses in rear of the batterieswhere they would be indistinguishablein the mass of buildings. The height ofthe coastline of Malta is so low that thehorizontal position finder was consid-ered necessary for the new long rangeguns.

Electric Position Finder

The electric position finder proposed byMajor Watkin for Fort Bovisand andPicklecombe in 1887 used the samepattern range table as that for thedepression position finder being usedin the battery. The observing stationscould be wholly outside the fort as inthe case of the depression positionfinder, one of these observing stationshowever needed to be of suitabledimensions for holding a chart or charttable. These instruments were onlyintended for works having lesscommand of 60ft. above mean tidelevel. the arrangement for groupingthe guns and for communicationbetween them and the guns was to bethe same as for those of the depressionposition finder. Three observingstations were required. two of theseneeded to be clear of the fort right orleft and the third at such a distance asto give and effective working base.Watkin proposed The following stationswere to be supplied with electricposition finders,

PortsmouthSpithead Forts 9 @ £60

Sheerness 4 @ £60LandguardFort 3 @ £60

Siting the D.P.F.

It was recommended that the observ-ing stations in which the instrumentswere to be placed should be situatedwell clear of the work if possible to theright or left and never immediatelyabove it. They were to be be sodesigned and placed as to beconcealed from the enemy and out ofthe probable line of his fire. Two sets ofobserving stations were to be providedin order that one set should be avail-able should the view from the other setbe impeded by smoke. As the instru-ment now provided required no charttable the expense of these stationswould be very trifling and thereforethere should be no difficulty in increas-ing their number as proposed. Theguns in the work were be divided intogroups, the number in each and theirdistribution to depend on the contourand structure of the battery. As all theguns in a group were to be laid withthis system with their axes parallel, theoutside guns of any group were not tobe further apart than 100 feet horizon-tally. Each group required a PositionFinder and dial, the latter to be placedin a convenient position in the centreof the group. The instruments were tobe connected with their dials bymeans of a five core armoured cableefficiently protected from interruptionby either the enemy's fire or othercauses. The instruments require onlyfour wires but the fifth would be avail-able for a firing wire or in the case ofinterruption for any of the others.

D.P.F. proposed sites

The depression position finder wasrecommended as being applicable tothe following stations :-Portsmouth; Needles passage, Dover,Portland, Malta, Gibraltar.The totals of Instruments were

Plymouth 30Portsmouth 8Dover 6Gibraltar 20Malta 30PortlandBreakwater 12

Grand Total £50 per instrument pluscosts £16,305. It was proposed to addCork, Forts Camden and Carlisle, Aden

Sources

Permanent Fortification for EnglishEngineers - LewisCoast Defences of England and Wales1856 - 1956 - Ian V. Hogg.Handbook for the 9-inch RML gun andmountings 1899 H.M.S.O.Artillery: its Origin, Heyday and DeclineO.F.G. Hogg 1970WO33/45 Minute 41,561 Abstracts ofProceedings of the Department of theDirector of Artillery for the Quarterending 30th. September 1884.WO33/45 Report on Trial on MajorWatkin’s Depression Position Finder atBovisand Fort 21st. and 22nd October1885.WO33/47 Abstracts of Proceedings ofthe Department of the Director ofArtillery for the Quarter ending 31stMarch 1887.


16 No.34 June 1995

Report on the Defences of Malta &Gibraltar by Major Callaghan andCaptain Clarke 1886Manual of Coast Fortress defence - 1914- PRO Kew WO33/697Manual of Coast Defence RangeFinding Part II - HMSO 1915 PRO KewWO33/711Details of Equipment of Her Majesty'sArmy Part 2 - Section XI . B - GarrisonArtillery WO 1891

Once more I am grateful to RobertChrismas for helping me with theapplied maths that is necessary tounderstand the intricacies of rangefinding.

In a future article I will attempt toexplain the working of the PositionFinder in more detail and describe thearrangements as found in FortGilkicker.

Report on the Account of Army Expenditure from 1888 to 1889211c The Volunteer Artillery received during the year a most important addition totheir equipment in the shape of no less than 226 guns. Many of these guns wererequired to replace others from various causes but amongst them there weresufficient to enable the authorised re-organisation of this arm of the service to becarried out to the following extent:-

27 x 40pr. RBL7 x 20pr. RBL33 x 16pr. RML all batteries of position

Carriages for all these batteries were also provided and a proprtion of ammunitionwagons and ammunition and store wagons, also equipments according toapproved lists and ammuntion at the rate of fifty rounds per gun. Further provisionof ammunition up to 200 rounds per gun was also proceeded with but suppliescannot be completed until accommodation is furnished at the centres formobilisation. These issues represent in stock value about £87,000

Taken from WO33/45 PRO KEW

VOLUNTEER ARTILLERY 1888

Documents

FIRING THE GUNS - 2