LOCOMOTIVE ENGINE. 453 



collar soldered upon it with a thin conical end, which is fitted into the tube /, and 

 held water-tight by the socket K, screwed on to the tube and bearing against 

 the collar of the suction pipe. 



The piece M, which is bolted upon the upper pipe G, is closed at the top by a 

 cap, P, screwed upon it, and has a tube cast on it like the bottom piece, 7, into 

 which the end of the delivery pipe, -N, is fixed by the screwed socket 0, exactly 

 similar to the suction pipe, H. The delivery pipe is bent round backwards, as shewn 

 in Plate LXXXIX., extending to the fire box, where it is fixed into a valve 

 box, in the same manner as the other end is fixed ; the pipe has to be bent in 

 this way that the ends may be turned in the same direction to allow them both to 

 be screwed into the sockets instead of having the screws at the two ends pulling 

 against each other. This box contains another valve like those in the pump, 

 and is fixed on to the fire box, communicating with the inside. The suction pipes, 

 K'K', (Plates LXXXIX., XC., XCI., and XC1I.,) pass under the fire box, and are 

 connected at the end to the pipes that bring the water from the tender, being sus- 

 pended by stays, s s, from the fire box. 



In the pieces L and M, are fixed the valves Q and R, which are shewn to 

 double the scale in figs. 30, and 31, where T is the valve seat, made conical and 

 with a groove outside to hold packing for fitting it water-tight when driven into its 

 place in the pump. The valve S is a ball, turned and ground truly spherical, 

 fitting water-tight into its seat in every position ; it is guided by the piece U U, 

 screwed upon the valve seat, and cut into four bars to allow passage for the water. A 

 pin, V, is screwed through the cap P, bearing upon the guide of the valve R, and 

 fixed by a set nut, W, to hold down the valve seat and prevent its being raised 

 out of its place by the force of the pump ; the lower valve seat does not require 

 holding, as the pressure is above it. 



The plunger B, fig. 29, is worked in and out of the barrel of the pump A, a dis- 

 tance of 18 inches, by the piston rod at each stroke; leaving a space behind it when 

 drawn out equal to its bulk, which is supplied with water through the suction pipe 

 and lower valve, and the water again forced out through the upper valve and delivery 

 pipe into the boiler when the plunger is pushed in. The internal diameter of the 

 suction and delivery pipes, and of the water way in the valve seats, is one inch. The 

 pump would force a quantity of water into the boiler at each stroke equal to the 

 bulk of the plunger for 1 8 inches in length, if the suction pipes were kept open ; but 

 the quantity is regulated according to circumstances by means of the cocks t' t' 

 fixed in the suction pipes, the handles of which extend upwards through the foot 

 board on which the engine man stands so as to be within his reach ; and the closing 

 these cocks causes the plunger to leave a partial vacuum behind it, and as the 



