" hi the ram shown in Fig. 4 the two escape-valves V and E are ar ranged to pass up freely through their seats, and are stopped by an air-cush , ion at the top. The waste water near ly all escapes at the upper valve V, small outlets only being provided in the lower valve E for permitting sand to escape if any should be carried into the machine. The closing is effected mainly by the upward press ure of the issuing stream against the curved shield S. When the valves are shot upward in closing, the shield en ters the air-chamber above it, in which it fits as a piston, and the momentum is thereby checked without the least shock. An air-cock is inserted in the top of the air-chamber at L, for regulating the amount of resistance offered by the air-cnshion. Additional weight, if required for opening the valves, is added on the top of the valve-stein at K; it is found, however, that the higher• the delivery head the less is the weight required, because of the reflux. Shifting valves were at first ap plied. but seemed unnecessary. Rams arranged in this manner work without noise or jar, and give a high efficiency for forcing four to five times the height of the propelling head, and are suitable in most cases for irrigating purposes; but when the resistance is increased, the elas tic blow• or percussive impulse of the current is not enough to raise the check-val•e C against the increased area caused by its lap.
-In Figs 5 to 8 is shown another arrangement of hydraulic rain, in which the escape-valve is opened by independent mechanism. The water enters at I, and the waste escapes at the bottom through four holes shown in the sectional plan. Fig. S. These holes are alternately covered and uncovered by the four wings of the oscillating valve V. which is mounted on a spindle S. The valve is opened by means of the water-wheel 11', and the tappet motion shown in Figs. 5 and 7. The two tappets, coming in contact at each revolution of the water-wheel, open the valve to such an extent as may be determined by the adjusting screw, set in the slot at A. As soon as the tappets disengage, the valve is closed by the traction of the issuing stream against its curved ribs or vanes, as shown in Fig. 5, the motion being arrested by the fail Tof the tappet-aria, Fig.?. In this manner the motions of the waste-valve V can be con trolled at will, mid a greater efficiency attained than with the ordinary method of employing the force of the issuing stream for closing the valve by lifting it. Experiments have not yet been made to determine the most effective motion of the valve with respect to the time of closing: but the indieations point to variable requirements in this respect, depending on the resistanee offered or the height to whMI the water is being