01, 02. Steam pipes, one end of each is screwed to the regulator, (See Fig. 9.) and the other ends to the receivers PP, to convey the steam from the great boiler into those receivers.
P , P2. Copper vessels called receivers, which are to receive the water which is to be raised.
Q Screw joints, by which the branches of the water pipes are connected with the lower parts of the receivers.
R1, 2, 3, and 4, valves or clacks of brass in the water pipes, two above the branches Q, and two below them; they allow the water to pass upwards through the pipes, but prevent its descent; there are screw plugs to take out on occasion, to get at the valves R.
S The forcing pipe which conveys the water upwards to its place of delivery, when it is forced out Trom the receivers by the im pellent steam.
T The sucking pipe which conveys the water up from the bottom of the pit to fill the receivers by suction.
V A square frame of wood or a box with holes round its bottom in the water, to inclose the lower end of the sucking pipe to keep away dirt and obstructions.
X A cistern with a buoy cock coming from the force pipe, so as it shall always be kept filled with cold water.
YY A cock and pipe coming from the bottom of the said cistern, with a spout to let the cold water run down on the outside of either of the receivers P, P.
The handle of the regulator to move it by either open or shut, so as to let the steam out of the great boiler into either of the receivers.
The mechanism of the regulator and the guages will be better understood from the section of the boiler shown in Fig. 10. R being the regulator moved by the handle Z in Fig. 8, 9, which can thus be brought to slide alternately over the mouths of either of the pipes 0 1, 0 2.
The two boilers D, L are fixed in a good double furnace, so constructed that the flame of the fire may circulate round them. Before the fire is lighted, un screw the guage pipes and cocks G and N, and at the holes fill the great boiler L two-thirds full of water and the small boiler I) quite full. When these pipes are again screwed as tight as possible and the water brought to boil by the fire under the large boiler II I, steam will be raised, and will endeavour by its elastic force to make its escape. This is effected by pushing
from you the handle Z of the regulator (it Fig. 10.) as far as it will go, when the steam will rush with great force through the steam pipe 0 1 into the receiver P 1, driving out all the air before it, and forcing it up through the clack R1 into the force pipe. When the receiver P I is thus thoroughly emptied and has be come very hot, pull towards you the handle Z of the regulator, which will remove the slide R, Fig. 10. from the mouth of the pipe 0 2, and place it on the mouth of the pipe 0 1, so that no more steam can come into the receiver P 1, when it passes freely through the other steam pipe and fills the other receiver P 2, heating it and discharging its air through the clack R 2 up the force pipe.
Having condensed the steam in the receiver PY by cold water, from the spout Y, a vacuum will be created in it, and as there is nothing at the bottom of the receiver P 1 to counterbalance the pressure of the atmosphere on the surface of the water at the lower spout V of the sucking pipe T, the water will be pressed up and will fill the receiver P 1 by suction, the water lifting hp the clack valve R 3, which after wards falling down prevents the water from returning that way.
The receiver P 2 being emptied of its air, admits the steam again through 0 1, and by its elastic force, which exceeds the weight of the column of water in the receiver and pipe S, it will press on the surface of the water and drive it up through the passage R 1 into the force pipe S, discharging it at the top as shown in the figure. In the same manner the receiver P 2 is alternately filled with water by suction, and then emp tied by the elastic force of the steam, so as to keep up a constant stream at the top of the force pipe S. When the water has half filled the force pipe S, it also fills the little cistern X, by which the condensing pipe YY is supplied. This pipe can be turned side ways by its handle n, so as to throw cold water on the outside of either of the receivers.