STATIONARY ENGINES.

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the bearings and raised parts for the drum, fly wheel- if so fitted,eccentrics, and other minor details, should be accurately turned;while all the eyes of the various fittings should be bored out tothe exact size, and held by means of keys bearing on a flat part of theshaft, keyways being cut in the parts. This is by far the cheapestand best mode of hanging the drum and centre pieces, fly wheel,&c.; the old mode of hanging these fittings with a number of keysin each is not to be commended, and has now become obsolete.

The feed pump is of the plunger type, and is bolted down onthe top of the bed plate at the end nearest the main crank shaft.It is desirable that the plunger should be of brass or Muntz metal,connected by means of a wrought-iron rod to the end of the gudgeonfor the crosshead—an eye is forged on this rod, and accuratelybored out to take the end of the gudgeon, and held in position witha set screw. When the pump is placed well back, the plunger isbetter balanced at the extreme IN stroke, as there is a considerabledistance from the pump gland to the centre of the crosshead whilein that position; and the plunger by this arrangement is not soliable to droop, as it would do were the crosshead working quiteclose up to the pump gland. The suction and delivery valves andseatings are of brass, fitted into cast-iron valve chests; an escapevalve should also be fitted, loaded with a certain weight, so thatwhen the attendant shuts the feed valve on the boiler, the water isforced past the escape valve, and finds its way by a pipe connectioninto the pond or cistern from which the supply is drawn. An airchamber should be fitted to some convenient part of the feed pipe,as by this means the flow is more uniform, and tends to lessen theVibration in the pipes when the engine is working at full speed.As these pipes are sometimes subjected to the influence of hardfrost, the engine rarely going all night, they should be properlyclothed and protected with a non-conducting material; and a smallplug tap should be fitted, so that all the water may be run offbetween the pump and feed valve placed on the boiler: these pre-cautions taken, there is no fear of breakage occurring, as has toooffen been the case otherwise; for when an engine is started in themorning with the water in the feed pipe frozen a fracture musttake place. In many arrangements the feed pump is dispensedwith, the boilers being fed with a separate steam pump. The steampipes must also be protected with feit and canvas sewn over, toprevent condensation. The exhaust pipe (when the waste steam