Locomotive Steam Engines. 33 



rather more than their diameter. The faces of these openings are 

 turned truly cylindrical, and the regulator valve has two projecting 

 faces accurately turned so as to cover the entrance to these pipes 

 as closely as possible. To the centre of the valve a long rod is 

 fixed, which runs through the boiler to the footplate, where there is 

 a lever fastened to it by which the driver can more easily regulate 

 the supply of steam ; for when he turns the rod by means of the 

 lever, he turns the projecting faces off" the apertures of the pipes, 

 and so allows a free passage for the steam to the cylinders. 



The piston is a circular plate of metal a little smaller in diame- 

 ter than the cylinder; this plate has two square grooves round its 

 edge, in which there are two square iron bands, — by means of 

 small holes in the piston the steam is admitted from the top of it 

 to the back of the top band, and from the bottom of it to the back 

 of the bottom band, so that when the steam is on it presses these 

 bands alternately tightly against the inside of the cylinder, and 

 thus prevents any leaking past the piston : but when the steam is 

 turned off", the bands contract and the piston runs free in the 

 cylinder, and thus avoids much wear and tear. 



The lubricator for keeping the cylinders oiled was next ex- 

 plained ; it consists of a copper ball placed in front of the engine, 

 and communicating with the cylinder by a pipe from the top of it. 

 This ball is filled with oil, and as soon as the steam enters the 

 cylinder, some also rushes into this ball through the pipe, and is 

 condensed there on account of the exposed situation of the ball, 

 the water then being heavier than the oil sinks to the bottom, and 

 causes the oil to overflow through the pipe into the cylinder. 



A novel and ingenious apparatus for filling the tender with 

 water without stopping was also mentioned : between the rails 

 there is a long trough, and beneath the tender is a scoop, the 

 bottom part of which can be lowered into the trough by a rod 

 working from the foot-plate ; the speed at which the scoop travels 

 through the water, drives the water up through a pipe into the tank. 

 By means of this apparatus the size and weight of the tender are 

 considerably reduced, and a train can run very great distances 

 without stopping. 



