Class Y.]

179

HYDRAULIC MACIIIXES, Ac.—AWARDS.

space is aided by the pressure of the condensed air in theair-chamber, anil when the stroke is completed, the stateof condensation of this air is, by the momentum of thewater in the suction-pipe, restored, causing it to rushthrough the passage by which that pipe communicateswith the air-chamber. Thus, by this contrivance, thesurplus work, or half the vis viva, which remains in thewater of the suction-pipe at the conclusion of eacli stroke,is stored up in the compressed air of the air-chamber, andhelps to begin the next stroke of the piston.

The nature of this action will be best understood fromthat of the hydraulic ram. The contrivance constitutes,indeed, in some respects, a union of the action of the ramwith that of the pump; aud, besides accomplishing theobject for which it was applied, appears to have the effectof considerably economising the power employed inworking pumps.

The suction air-chamber has been added to a commonsuction-pump, exhibited by Mr. Self (452, p.235}, in theAgricultural Department, where, being made of glass, itsaction was readily to be seen. Tt is also introduced ina class of small pumps, called “fire-syringes,” exhibitedby Mr. Baddeley (409, p. 227), and Messrs. Shand andMason (410, pp. 227, 228). Except in the case of theCanadian engine, it does not, however, appear to have beenapplied in any of the larger class of engines exhibited. Itshould probably be constructed of much larger dimensionsthan have been given to it in either of these engines.

Awards in Section D.

No. 1S1 (Canada ), p. 968. G. Perry and Brothers,Montreal . A carriage fire-engine, to be worked by fortymen. Highly commended for the large proportion of thesectional area of the suction-pipe to that of the barrel, thelarge dimensions of the valves, the application of an air-chamber to the suction-pipe, and the general arrangement.In the experiments made by direction of the Jury, noother engine threw a column of water so high as this, ordischarged so great a body of water per man, or yieldedso great an amount of work per man measured by thevis viva of the water passing the nozzle. A Prize Medalis awarded.

No. 1310, p. 1239 (France ). Letkstu, 118 Iiue duTemple, Paris . 1. Afire-engine without a carriage, tohe worked by ten men. 2. A marine fire-engine, to heworked by tern men.

Highly commended for the ingenious, simple, and eco-nomical arrangement of the pistons, the large dimensionsof the valves, and the large sectional area of the suctionand force-pipes, in comparison with the barrel.*

The piston is a hollow perforated cone of brass, to theinterior of which is applied a circular piece of leather,like a filtering paper to a funnel, but having a sector cutout, instead of being folded ; the radial edges of theleather overlap, and its periphery projects beyond theedges of the cone, adapting itself to the internal surfaceof the barrel.

When this piston is to be used for suction, it is fixed tothe rod with the base upwards; and when for forcing,with the base downwards. In the return stroke, the waterpassing through the perforations of the brass cone finds apassage between the loose radial edges of the leather,which it separates.

The valve in the air-vessel is a simple disc of leather,screwed down at its centre on a perforated plate. TheJury have awarded the Prize Medal for these engines.

No. 410, p. 227. Shaxd and Mason, 245 BlackfriarsRoad, London . London Brigade carriage fire-engine,worked by twenty-eight men. Metallic valves; for whicha Prize Medal is awarded.

Moses Merryweather, 63 Long Acre, London (401,pp. 226, 227, and Illustrations). London Brigade carriagefire-engine, to be worked by thirty men. In compliancewith a wish expressed by some of the Exhibitors, the

* The pumps of Letestu gave a greater useful effect, inproportion to the power expended in driving them, thanany others, in the dynamometrical experiments of ColonelMorin at the Paris Exhibition of 1849. This useful effectdid not, however, amount to one-half the power expended.

merits of the above-mentioned engines were subjected to| trial in the presence of the Jury, and the following tablecontains the results of the trial. The engines were workedby soldiers of Her Majesty’s regiment of Grenadier Guards,obligingly placed at the disposal of the Jury by theirColonel. Those who worked upon the different enginesappeared of the same average size and strength. Theirwhole effort was in each trial given to the work, and itwas so intense as to be continued with difficulty for threeor four minutes. No more certain means of comparisoncould perhaps have been adopted under the circumstances,but if more time had been allowed for the labours of theJury, and if arrangements could have been made to drivetne pumps by steam-power, and to apply to them the dy-namometer of MM. Poncelet and Morin, the relation ofthe useful effect of each to the power expended in workingit could have been determined with a precision not other-wise attainable.—(See Table, page 18U.)

No. 44S, p. 234. A Prize Medal is awarded to S.Cheavin, Spalding, for a pump for taking the surface-water only of a well, and at the same time filtering it.The suction-pipe is jointed, so as to allow of one portionof it moving in a vertical plane. The moveable portion issupported by a ball float, so that its open extremity mayalways be near the surface. To prevent impurities fromentering, this extremity is protected by six hollow conesof copper finely perforated, of different degrees of fineness,covering one another.

Honourable Mention is made of the following Exhi-bitors ;—

No. 402, p. 227. William Stialders. Fountain pump.Its peculiarity lies in the connexion of the bucket with thecylinder by a collar of leather blocked into the shape ofa truncated cone, its smaller end being fixed to the bucket,and the larger to the barrel. The play of the piston islimited to the height of this leather cone. The cone issupported by a metal collar of a corresponding conicalform, from which it unfolds itself as the bucket playsbackwards and forwards. Commended as an ingeniousand useful application of a known principle.*

No. 935, p. 1225 (France ). Xilli's, —, jun., Graville,near Havre . A double pump, with large cylinders and six-inch valves, constructed on the same principle as ShaJders’pump; mounted upon a carriage to be used in excava-tions. Commended for convenient arrangement and goodworkmanship.

No. 424, pp. 232, 233 (Illustrations, p.233). Warner,John and Sons. Deep well force-pump. Commendedfor the facility with which the valves can be removed tobe repaired, and for good workmanship.

No. 409, p. 227. Baddeley, William, 29 Alfred Street,Islington . A portable farmer’s fire-engine, applicablealso as an agricultural force-pump. Commended for easyaccess to the valves, the application of a jet-spreader to thenozzle, and for simplicity and convenience of arrangement.

No. 299, p. 1191. Leclerc, H. Eugene, Maker, 105Quai Valmy, Paris . A revolving pump, and various jets-d’eau. Commended for ingenuity of combination andarrangement.

Centrifugal Pumps.

In these pumps, water admitted at the axis of a hollowwheel, traversed by vanes and made to revolve rapidly,is expelled at its circumference.

The pipe by which the water roaches the axis of thewheel (or the reservoir which feeds it) becomes, underthese circumstances, a suction-pipe, and if the reservoirinto which the water is received from the periphery ofthe wheel be closed, and a pipe be carried from it upwards,the latter becomes a force-pipe.

The greatest economy of power in such a pump maybe expected to be attained when there is the least pos-sible loss of the vis viva of the water in its access to thewheel, and when there remains the least possible vis vivain it when it leaves it. For if there be any loss of thevis viva of the water in its ingress to the pump which

* A pump on this principle is described in the Traite deMecanique of Borgnis. Paris , 1819. The invention isthere ascribed to MM. Denisart et Deville, MachinesHydrauliques , p. 52; it is probably, however, more ancient.

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