The joints, as a
rule, are riveted together, with occasional lead joints to admit of slight
movements in the pipe.[4] The pipe was coated by placing each joint in a
bath of boiling tar and asphaltum; to insure the most thorough coating, it
is necessary to keep the pipe for ten or fifteen minutes in the boiling
mixture. A cast-iron stop-gate is placed at the lower end of the main, and
also one at each of the branches. Cast-iron man-holes are attached to the
main, which, although they have given no trouble in this particular case,
are very objectionable for high pressures, as it is difficult to avoid
ruptures with cast and wrought-iron combined, owing to the great
difference in the elasticity of the two metals. The long seams of this
pipe are double-riveted, and the round seams single riveted; at the lower
end, iron of No. 6 gauge is used. From the end of the main, the water is
led to the several wheels by branches of smaller diameter.
[Footnote 4: With buried wrought-iron pipe this precaution is unnecessary,
as the elasticity of the iron will admit of the movement due to changes of
temperature, without injury to the rivets.]
The water is delivered at the hoisting-wheel with a total head of 542.6
feet. For power and for mill uses, etc.
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