STATIONARY ENGINES.

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The cylinder for these engines is a plain casting, with steam andexhaust ports suited for the ordinary slide valve: one steam portat each end, and a central port for the exhaust. It is preferable tofit a cover at each end, more especially for large diameters, as theboring bar requires to be of a large size to bore out truly these long

Fig. 150.—Colliery Winding Engines. Side Elevation and Ground Plan.

cylinders free from Vibration, and the hole for the bottom bush inthe stuffing box on a solid end is too small in diameter for anordinary sized boring bar. There is a deep stuffing box on eachcover, fitted with a gland in the usual manner. The piston rodpasses through both these boxes, an arrangement which takes part

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