STATIONARY ENGINES.

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A variety of forms of blowing engines are now in use, viz. thebeam, the side-lever, the vertical, and the horizontal, which we willnotice in succession.

The high-pressure beam engine has been largely used for blowingpurposes. Its main beam is cast in two halves, held together bydistance pieces; the steam cylinder is placed at one end of thebeam, and the blowing cylinder at the other. The connecting rodand crank shaft are placed between the steam cylinder and themain centre of oscillation of the beam, and the cold water andfeed pumps between the blowing cylinder and the main centre ofoscillation.

The steam cylinder is a plaincasting, with oblong branchesat the top and bottom for thesteam ports, which are madeas short as possible. Whenthe stroke of the piston is longit is desirable to have thesteam valves so arranged thatthe cubical capacity of thepassages on the cylinder sideshould be as small as practi-cable, by which means muchsteam is saved at each stroke,as compared with some ar-rangements where the pas-sages extend from the top to

the bottom of the cylindei. A Fig. 152.—Steam Cylinder and Cover,

square base is cast along with A , c y imd er. b B, Steam ports. c, Cone plug.the cylinder, having a hole inthe centre for the boring bar topass through, which is afterwards filled up with a plug or cover. Partof the base is hollowed out on the opposite side from that of thesteam ports, to give the necessary clearance for the main connectingrod. The body of the cylinder has suitable belts cast on, and alsoa projecting moulding near the top for supporting the platform.The cylinder is firmly bolted down at each corner of the base platewith long bolts, passing down through lioles left in the foundations,and secured at the under end with plates and cotters; these beamplates extend across the structure from hole to hole. A cast-iron

D, Cover.

e, Raised lip on flange for catching the oil.f, Part cut out for the connecting rod.