STATION AR Y ENGINES.

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secured to the floor in the fly-wheel pit. There are two fittedunder the wheel at each end. On the vibrating centre or fulcrumof the long brake lever, a shaft carried on suitable bearings has adouble-ended short lever keyed on it, fitted with eyes and pins;from these joints two side rods pass along, one on each side of thefly wheel, and are secured to eyes on the wrought-iron pieces fortaking the friction blocks. Both brakes are so fitted, and with amovement of the long lever the off-brake is drawn against theperiphery of the fly wheel, while the near one, fitted with short rods,transmits a compressive strain, which of course the short connectinglinks are better calculated for. With parallel winding drums thearrangement is somewhat different. The drums have two sidesheaves for each; the two centre ones are placed sufficiently wideapart to take a strong ring which is fitted to the skeleton sheaves,this serving as a brake wheel, which in this arrangement is actedon by a strap lined with wood placed underneath it, fitted withsuitable levers and shafts. Some authorities consider that thisbrake wheel is not so well placed as in the former example, for thestrain acting on the centre of the shaft between the two enginestends to throw undue stress on the shaft. But we must not losesight of the fact that when a separate fly wheel is used, placed atthe side of the drum, the adjoining bearing has more duty to per-form, and it may be concluded that with extra strength given tothe shaft, to resist the pressure of the brake, the intei'mediate brakewheel can be used with advantage, equalizing the wear on thebearings, which is an important consideration in coupled engines.

In some examples where steam pumps are fitted, instead of theusual feed pumps, thus simplifying the engine considerably, the feedwater is heated in its transit to the boilers by passing through anumber of small tubes fixed in piates, inclosed in a cast-iron cylinder;the exhaust steam enters this cylinder, surrounds the tubes, andtransmits its heat to the cold water passing through them. Someengineers blow the exhaust steam into a receiver, and the cisternplaced at the end of the exhaust pipe for collecting the Condensedwater is a similar contrivance: the steam is blown over the surfaceof the water, which becomes thoroughly heated. Of course thesteam that is not Condensed is blown up the chimney in either ofthose feed-water heaters. In the former plan there is no troubleattending the Operation, as the feed water is simply passed throughthe small tubes in its transit from the feed pumps; but the latter