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KENNETH ALLEN, M. AM. SOC. C.E. (by letter).--From its lightness,
toughness, flexibility, and the facility with which it can be laid, wood
pipe has manifest advantages for use in inaccessible places and where
handling is difficult; loss in transportation is almost negligible, it
will stand much unequal settlement without cracking, and ordinary leaks
are easily repaired.

The coating of the bands is of such great importance that it should be
inspected very thoroughly, in order to remedy defects before the
back-filling is done. The writer has found Durable Metal Coating an
excellent preservative. Bands coated with this preparation were buried
in a salt marsh, and, after a year, the metal was found intact and the
coating fresh and elastic. This coating, however, does not adhere very
firmly to a smooth metal surface, so that, with careless handling,
patches may become rubbed or torn off.

There is no advantage in coating the surface of the pipe. To prevent
decay, such pipe should carry water under pressure or be laid in a
saturated soil, so that the wood of which it is made will always be
saturated, and coating the wood may interfere with this. Under these
conditions the life of such pipe is not known, but it is evidently very
great. Large quantities of wood pipe have been removed from trenches in
Boston, New York City. Philadelphia, Baltimore, and elsewhere, usually
in perfectly sound condition. It was commonly made of logs of spruce,
yellow pine, or oak, from 12 to 18 ft. long, 12 to 24 in. in diameter,
and with a bore from 3 to 6 in. in diameter. Some 6-in. pipe taken up in
Philadelphia had an external diameter of 30 in. The ends were usually
bound with wrought-iron collars, and adjacent lengths were connected by