96 Civil and 3[echanical Engineering.

too often construed as exhibiting our inability to design and build that which is more durable and better.

A friend of the writer, traveling in Switzerland in 1867, inves. tigated a saw-mill which he found there for cutting fir timber, which he describes as follows : --The water was spouted with wooden troughs to an overshot wheel of about 12 feet diameter. In the axis of this wheel there were inserted wooden lifters similar to those used for operating " Cornish stamps." The saw with its frame or attachments was lifted up by these lifters, and then "fell down" by its gravity in making the cut. To arrest the downward stroke and to determine the range of movement a strong beam extended down from the saw-frame, and came down at each stroke upon a bed of saw-dust and ships at the bottom. I t is to be regretted that there was no sketch of this piece of engineering taken at the time, but from the description it is safe to assume that no such thing was ever seen in :North America, nor any parallel for it. This is mentioned as contrasting with the general knowledge of saw mills existing here.

(To be cont inued.)

DISTILLING APPARATUS FOR STEAMSHIPS, Editors Journal Franklin Institute :

THE importance of a distilling apparatus, fkom which may be obtained an ample supply of palatable, Wholesome water t i s s o great on board all merchant steamers making long voyage¢ as well as on our naval vessels, that I am confident that the following report upon the only apparatus of this kind Which has yet fully met this great want, will be read with interest bya l l who have been or who expect to be called upon to make an ocean voyage, as well as by engineers generally. R. •. v.

:Naval Academy, Juno 81 1870.

"Mare Island Navy Yard, March 11, 1870.

" S I R ; .x- * ~ -:¢ * The water obtained on shipboard by the condensation of steam from the boiler, being the result of pure distillation, is wholly unmixed with air, is quite warm as it comes from the condenser, and is unfit for use until after several days exposure in tanks. These tanks are situated in the hold of the vessel, and the air imbibed by the water is saturated

Distilling Apparatus for Steamshi2s. 97

with the bilge-water gases which accumulate in that unventilated apartment.

"The purpose of the invention of 2d Assistant Engineer George W. Baird, is to saturate the water of distillation with pure atmos. pheric air at the moment of condensation, thereby furnishing it thoroughly aerated, cool, and potable as it flows from the condenser.

"To effect this, an air injector, )., of very simple construction, is attached to the steam pipe, which is of no greater cost and bulk thafi an ordinary cock, and surrounds the pipe so that the current of steam induces an entering air current, and delivers it into the condenser against considerable pressure.

"The steam to be condensed, together with the quantity of air required for its proper aeration, thus enter the condenser thoroughly mixed, and, being in contact with each other, molecule to molecule, the water of condensation encloses as much air as it can l~old, and flows from the condenser in so super-aerated a state that aii~'bubbles from it adhere to the sides of any vessel into which it may be drawn.

"As thus delivered, the water has nearly the atmospheric tem- perature and is immediately potable; being already saturated with pure air, it cannot be afterward impregnated with the foul air of the hold.

"To still further oxygenize the air in the water, the steam pipe is passed through a vessel, •, containing a mixture of peroxide of manganese and chlorate of potash ; the oxygen, being slowly evolved by the heat of the steam, is conveyed by a small pipe, r', to the

VOL. LX.--THIRD SERIES.-- ~]'0, 2.--AU(tUST, 1870. 13

98 Civil arid .~£echanical •ngineering.

condenser, where it is absorbed by the water in such proportion that it acquires the taste of good drinking water.

"Incidentally, Mr. Baird's process adds materially to the cooling power of the condenser by the amount of cold air drawn in with the steam.

"The parts added to the ordinary condenser, by Mr. Baird, are the air injector, and the vessel containing the mixture of black oxide of manganese and chlorate of potash; they add but slightly to the cost and weight of the apparatus, while they add materially to its effect.

"A filter, D, of animal charcoal was used to remove any organic substances that might be brought over from the boiler, the water of which, in our experiment, was drawn from the bay, quite muddy and salt, and containing much vegetable and animal matter.

" In the experiment which we witnessed, the atmospheric tern. perature was 70 ° Fahr., and that of the aerated water was 72½ ° F. We are of the opinion that Mr. Baird's system of aeration may be beneficially used in all vessels of the navy."

The above report was made by a board of naval officers, Captain Reed Worden, chairman. Three chief engineers of the navy and two surgeons were among the members.

SURVEY OF THE NICARAGUA ROUTE FOR A SHIP CANAL, BY COL. O. Wo CHILDS, C. ~.

(Continued from page 39.)

Brilo Harbor.

A harbor connecting the canal with the Pacific at Brito is to be formed by the construction of a jettie o r b r ~ a t e r , by excava- tions to extend from within the moles of the jettie at 17 feet depth o~ water at low tide, to the foot of the lower lock, and by the con- struction of a wharf along its northwesterly side, surrounded by a wall of stone masonry.

From the lower lock, the base of the hill bounding the valley on the westerly and northerly sides, lies nearly parallel with and from 4 to 600 feet from the cut below described for the artificial harbor. The hill has an'elevation of from 2 to 300 feet, and ex- tends, in a westerly direction, 50 chains, to the water-line of the coast at high tide. From this point, with the coast extending off upon a line 'nearly at right angles to the left, the hill continues with a slight curve, als% to the left, and with nearly a vertical face