Chap. XVII.

MACHINES FOR RAISING WATER.

1203

the same time that in the pipe G L, being no longer forced, will close (he upper valve ; thewater in the pipe of communication Y V, driven by that from the cistern C, will open t elower valve in GL, again drive the piston R towards B D, while the other S will in itsturn force that which had driven it forwards until the axle Q having arrived at N O,will make a quarter revolution, closing the escape and opening the supply pipe : this willagain perfnit the water from C to drive the great piston, forcing that in the small barrel asbefore, closing the lower valve, and opening the upper. Thus the alternate motion of thocock will make the water rise to the cistern M, provided the product of the circleof the small cistern, multiplied by the height of the column FL. he less than the productof the circle of the great piston multiplied by the height of the fall C 1).

Fig. 1881. shows how the cock is opened and shut alternately. The whole machine iscarried on stout timbers, to which are attached two uprights supporting an iron spindle C D :on this as a centre an iron right angle O V II I revolves; the arms G H, K !. have claws at

Fig. 1881.

their extremities, and the rod V O a weight, at O, of 9 or 10 pounds ; this turns with the axleCD. A stirrup Qll plays on it, the axle being rounded at the rings Q and T.The iron rods E A and F/also move with the axle C D. The stirrup is traversed by twobolts L and M, the second of which passes through the branch Z of an iron fork,having a tail ZNP attached, the extremity of which works the key of the cock, which isprevented from going too far by a brace O. The rod X traversing the two pistons has aroller A B at each extremity, which alternately driving the two rods E A, F/, before themthat move the axle C D, and consequently H 1 V O, but not the stirrup, which remains inits position until moved by the action of the weight O.

Suppose the stirrup in the situation represented by the upper Bgure, and that the supplypipe be open, in order that the water may drive the great piston forward, the roller Adriving the rod E A will raise the weight O towards the right, and when arrived at thepoint E, the weight having passed the perpendicular will suddenly fall; the claw I Kthen meeting the bolt L, will oblige the stirrup to pass to the left, and drive the rod EX Fbackwards, at the same time turning the key of the cock ; thus directly the axle Xarrives at its extreme point to the left, the escape of the weight will shut oft the supplyand open the escape-pipe. The rod F f having performed the same operation will bedriven forwards by the roller B, in the same manner as the preceding, because the escape-pipe being open, the small piston will be driven back, and the weight O raised to pass fromright to left: when it is a little beyond the perpendicular, the claw I K will take up itsfirst position, meet the bolt L, drive the stirrup forward, thereby turning the cock, closingthe discharge and opening the supply pipe, the water from which will again drive thegreat piston, and cause it to execute its first operation.

'Hie axis C D should be placed at the middle of the open barrel, so that the three pointsa, 1), A may form an equilateral triangle in the same plane, whose base a A may he equal tothe course of the rollers between the points where they touch the rods E A, F f when they

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