194

MODERN STEAM PRACTICE.

to do. The second lift is situated 47 fathoms under the adit, andis provided with two suction and two delivery clacks. The thirdlift is 80 fathoms under adit; the fourth 120 fathoms, and the draw-ing lift 140 fathoms. It is not advisable to put in a lift of pumps

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Fig. 124.—Pit Work, showing Pumps, Rods, Cisterns, &c.

with ordinary valves more than 40 fathoms long, because the valveswill not stand the wear and tear consequent on the great pressureof the column of water. For ordinary use the clack valve with