Chap. XVII.

ON PUMPS.

1187

Fig. 1835.

considerably below, to a height considerably above the surface of the earth; this casecomprising the two former, both suction and forcing-pumps must necessarily be employed.

Fig. 1834. represents a suction-pump adapted to raise water from a well or cistern : itconsists of a leaden pipe 2 inches in diameter, dipping into the water, having its extremitycurved and resting on a block of stone or wood. To this is fitted another leaden pipe, 5inches in diameter, forming the pump-barrel; its M h

lower extremity takes off to adapt itself to thesuction pipe, and near their junction a woodenplug D is fixed, perforated by a circular aper-ture to which a clock or valve is fitted openingupwards, to prevent the descent of the columnof water in the barrel. The piston is a similarplug, E, furnished with a valve, also openingupwards. To the upper part a band of leatheris nailed, which fits the barrel rather tightly;the piston is attached to the rod by an ironstirrup. The power applied to the handle Kworks the bent lever M A I, whose arm L K is80 inches,.and LM 5; thus the power is £ ofthe weight, here expressed by that of a columnof water 5 inches in diameter, and in heightequal to that of the discharging pipe P abovethe level of the water. The tools F and G serveto draw up the lower valve, or to tighten it bystriking it with the circular head of F. Todraw it out, the valve O is first raised with thehook G, and the whole is then drawn up withthe end II.

Fig. 1836. is a pumpwith lever A working twopiston rods, B, C, one ofwhich is raised at the sametime that the other is de-pressed, and may be usedwhen the water is too lowto be raised at a singlestroke. For example, if awell were 40 feet deep, apump might be placed atabout half its depth, andanother at the surface ofthe ground; the rod Cwould then raise the waterto a height of 18 or 20 feet,whence it would be broughtto the surface by B.

Fig. 1837. is a suctionpump worked by a balanceE ; the power is applied toa cord A, and raises theweight B, which by sinkingraises the rod C. Thispump is well adapted toserve two adjoining proper-ties, by attaching a cord tothe arm D of the balance,and passing it throughthe party wall, but oneof the discharging pipesmust be closed when theother is in use.

Fig. 1838. shows amethod of working twosuction pumps alter-nately, so as to producea continuous stream ; thewinch A, to which the

Fig. 1834.

TV

Fig. 1836.

Fig. 1837.

4 G 2