water. The aqueduct
is a pipe 6 ft. in diameter, and of a total length of 6 m.; for a
distance of rather more than 5 m. it is formed of wooden staves, the
remainder, where the head exceeds 117 ft., being of steel. It is laid
in a trench and covered to a depth of 3 ft. The greatest pressure on
the steel pipe is 200 lb. per sq. in., and the thickness varies from
3/8 to 11/16 in. The pipe was constructed according to the usual
practice of marine boiler-work for high pressures, and each section,
about 9 ft. long, was dipped in asphalt for an hour. These sections
were supported on timber blocking, placed from 5 to 9 ft. apart, and
consisting of three to six pieces of 6 X 6 in. timbers laid one on the
top of the other; they were then riveted together in the ordinary way.
The wooden stave-pipe is of the type successfully used in the Western
States for many years, but its diameter is believed to be unequalled
for any but short lengths. There were thirty-two staves in the circle,
2 in. in thickness, and about 20 ft. long, hooped with round steel
rods 5/8 in. in diameter, each hoop being in two pieces. The pipe is
supported at intervals of 8 ft. by sills 6 X 8 in. and 8 ft. long. The
flow through it is 250 cubic ft. per second.

Santa Ana.

The _Santa Ana Canal_ was constructed for irrigation purposes in
California, and is designed to carry 240 cub. ft. of water per second
(_Trans. Am. Soc. C.E._ vol. xxxiii. p. 99). The cross section of the
flumes shows an elliptical bottom and straight sides consisting of
wooden staves held together by iron and steel ribs. The width and
depth are each 5 ft. 6 in., the intended depth of water being 5 ft.
The staves are held by T-iron supports resting on wooden sills spaced
8 ft. apart, and are compressed together by a framework. They were
caulked with oakum, on the top of which, to a third of the total
depth, hot asphalt was run. The use of nails was altogether avoided
except in parts of the framework, it being noticed that decay usually
starts at nail-holes. It was found possible to make the flume
absolutely watertight, and in case of repair being necessary at any
part the framework is easily taken to pieces so that new staves can be
inserted. The water in the flume has a velocity of 9.6 ft. per second.
The Warm Springs, Deep, and Morton canons on the line are crossed by
wooden stave pipes 52 in. in diameter, bound wit