STEAM-ENGINES. Ac.—AWARDS. [Class V.
The advantages to be obtained by working steam ex-pansively — long known to men of science — are nowgenerally acknowledged. It is, indeed, obvious that byadmitting the steam to the cylinder at a higher pressurethan that of the load , atid cutting it otf before the stroke iscompleted, the piston and the mass it carries with it aredriven on with a continually increasing velocity, until bythe expansion of the steam— after the closing of the valveby which it is admitted—its pressure is reduced to anequality with the load : when the piston does not stop —by reason of the momentum it has acquired—but iscarried on, the steam yet further expanding, until thestroke is at length completed and a cylinder-full of steamis discharged, expanded considerably below the pressureof the load. "Whereas by working without expansion, atwhat is called full pressure, a cylinder-full of steam isexpended at every stroke of (he pressure of the load.
The Jury has had to adjudicate on various expedientsfor thus working engines expansively, called expansiongear.
Awards in Section A.
No. 8, p. 211, and Illustration, 212. Jonx Penn andSon, Greenwich. 1. A pair of 12-liorse power oscillatingcylinder direct-acting engines, for river navigation, oflight construction and good workmanship for small vessels.
2. A pair of 30-liorse power patent direct-acting engines,called trunk engines, for driving a screw' propeller.
In these engines, which are similar to those of II. M.steam-ships “Arrogant” and “ Encounter,” the piston-rod is widened into a hollow cylinder called the trunk,14 inches in diameter, projecting through both ends of thesteam cylinder (2 ft. 4 in. in diameter), and having theconnecting-rod jointed to its centre; the width of thetruuk, allowing for its play at every stroke (16 in.) inthat position, and the stuffing-boxes serving as guides.A considerable economy of space is thus effected, andsome costly parts of the machinery are dispensed with.The circular form of the ordinary piston being by thiscontrivance converted into that of a circular ring, agreater diameter of the cylinder is required to obtain thesame area to receive the pressure of the steam, and agreater periphery has to be kept steam tight. There isalso a radiation of the heat of the steam in the cylinderfrom the internal surface of the trunk, to which the or-dinary engine is not liable, and a greater surface externallysubject to this radiation.
The ordinary packing of a stuffing-box at one end is,moreover, in this engine, enlarged into that of the largeconvex surface of the trunk (14 inches in diameter) atboth ends; and the difficulty of keeping the packing ofthese steam-tight, is increased by the lateral strain, towhich, serving as guides, they are subjected.
These are practical disadvantages which may, fornautical purposes, be compensated by the economy of‘space which is effected in this engine. It is from thisconsideration that the Jury has included it, with theriver engine, in the award which it recommends of a•Council Medal to the makers.
No. 119, p. 1155 (Belgium). Cockerill, J., Seraing ,"Liege. 1. A pair of 140-horse power vibrating cylinder'engines, for the navigation of the Rhine . The framingand paddle-centres, usually of cast-iron, being in these !engines made of wrought-iron, the requisite strength is .obtained with less weight.
The vibrating cylinders being so placed on oppositesides of the crank that each piston completes its stroke in :an inclined position of its cylinder (and, of course, 'when 1the stroke of the other piston is incomplete'), the samecrank-pin is made to serve for both pistons, and a singlecrank supplies the place of the two at right angles to oneanother, commonly employed to pass the dead points.
2. An outside cylinder locomotive engine, of goodconstruction and workmanship ; with a small donkey-engine attached, for keeping up a constant supply ofwater to the boiler when the engine is stationary.
3. An oscillating direct-acting three-horse power por-table engine and boiler, so combined that the weight ofthe boiler gives stability to the working parts of theengine fixed to the side of it. The arrangement is
| simple ; the inside of the boiler may be easily cleaned,and the working parts reached.
4. A small donkey-engine, with its pumps and valvc-, boxes complete, for a steam-boat; to apply usefully the: steam whicli would otherwise be blown off through thewaste-steam pipe, in filling the boilers, pumping thewater from the bilge or from the sea to wash the decksor sails, &c.; and in case of need, to extinguish fire.A Council Medal is recommended for this collection otmachines.
No. 220, pp. 1184-1186. See Illustrations, pp. 1185,1186 (France). Fromont and Sox, Chartres . A doubleturbine, constructed on the system of M. Fontaine Baron.The turbine is a hydraulic machine—of frequent use inFrance but almost unknown in England—which, instead ofrotating vertically, as water-wheels usually do, rotates ho-rizontally. 'When constructed with a careful reference tothe principles on which the efficiency of all hydraulic ma-chines depends, the turbine possesses these advantages:—*
1. It occupies a small space. 2. Turning very rapidly,it may, when used for grinding flour, be made to com-municate the motion directly to the mill-stones. 3. Itworks under water. 4. It works equally well undersmall and great falls of water. 5. It yields, whenproperly constructed, and with the supply of water forwhich it was constructed, a useful effect of from 68 to70 per cent., being an efficiency equal to that of anyother hydraulic machine. 6. The same wheel may bemade to work at very different velocities without ma-terially altering its useful effect. This last property isone of great importance in certain applications, andconstitutes an advantage of this machine over mostothers that have their established rates of working; fromwhich it is not possible to deviate without a proportionatesacrifice of power.
The turbine of M. Fontaine Baron, to which theJury recommends the award of the Council Medal,appears, from experiments made on its efficiency, to beone of the most successful of the modifications of thatform under which Fourneyron first introduced thismachine in France , in the place of the old horizontalwater-wheel.
The following exhibitors were awarded the PrizeMedal
No. 6, p. 211. Watt, James , and Co., 18 London Street,London, and Soho, Birmingham . A pair of horizontalcylinder direct-acting marine engines, of 700-horsepower, for driving the screw propeller.
The two cylinders of each engine'are placed oppositeto one another athwart the ship, and work, by means ofguides and connecting-rods, on the same crank of theshaft which carries the propeller. The cranks of the twoengines are fixed at right angles to one another.
No. 1. p. 210, and Illustrations. Atherton, Charles,H. M. Dockyard, Devonport. Patent expansion gear, bywhich the variations of the expansion may be registeredwhilst the engine is working.
No. 49, p. 219. Collinge, C., and Co., 65 Bridge Street,Westminster. A new and simple method of reversingthe slide of an engine, whereby the direction of itsmotion may be more easily changed.
No. 39, p. 218. Clayton, Shuttleworth, and Co.,Lincoln. A six-horse power oscillating cylinder direct-acting portable steam-engine, of plain and simple con-struction, having a good arrangement of the slide, andis easily manipulated.
No. 3, p. 210. Smith, F. P., Greenwich. A completeseries of models, illustrating the gradual advance andimprovement of the screw propeller; whicli was proposedand brought into general use by this gentleman.
No. 507, p. 1203 (France ''. Fladd, II. P., 27 Rue JeanGoujon, Paris . A high-pressure direct-acting five-horsepower steam-engine. The revolving parts are wellbalanced throughout; whereby the strain upon the bearings,