Chap. XVII.

MACHINES FOIl RAISING WATER.

1209

into the cistern E F, where its motion is further calmed by another rim G ; from thence itis distributed by gauges of different sizes into all the basins comprised between E F andH 1, having each a pipe at the bottom to conduct the water to its destination : each of

O Oy

Fig. 1893.

Fig.1891.

Fig. 1894.

9 O O O o

0 O O

^OO

5ooO|

Fig. 1892. FOUNTAIN OF ST. CATHERINE'S. Fig. 1895.

these descending pipes is closed by a valve A ( Fg. 1893.), attached to a rod, whose extremityterminates in a screw working in a nut C ; the valve is raised and lowered by means of akey E; to prevent extraneous matters from entering, each valve has a cover of metalpierced with holes, and opening on a hinge.

Experiments have been made on the effects of flexures or bendings in the pipes whichconduct from the reservoirs of water-works : the pipes were perforated with small holes,to allow the escape of the air, and at each end a tube, 2 inches in diameter, was solderedon, which united with the reservoirs: and it would seem that a curvilinear pipe, in whichthe bendings lie horizontally', discharges less water than a rectilinear pipe of the samelength, and that 3 still greater diminution takes place when the flexures are placed in avertical plane. When there is a number of contrary flexures in a large pipe, the air some-