As a further comment, it might be stated that a water-tight concrete for
the tank could have been obtained by adding from 8 to 10% of hydrated
lime to the 1:2:4 mixture. This seems advisable in all cases where a
water-tight concrete is necessary. The interior plastering could then
have been done as a further precaution.


A. KEMPKEY, JR., JUN. AM. SOC. C. E. (by letter).--Mr. Couchot's
statement, that the 3-in. inside and outside sheets forming the tank
casing do not act together, is quite true, and it was not expected that
they would, other than to protect the steel and form an ornamental
covering for it.

There is certainly adhesion between concrete and steel, even though the
steel be in the form of a thin shell, and in a structure of this kind
where the steel is designed, with a low unit stress, to take all the
strain, and where the load is at all times quiescent, it is difficult to
see how this bond can be destroyed; the writer feels no concern on this
score.

Mr. Markwart's statement, that the steel tank enclosed within the
concrete of the upper cylinder, presumably to provide a water-tight
tower, will not fulfill this latter requirement, is not true, as shown
by the statement in the paper that the only leakage which occurred was
that which passed under the tank, the entire remaining portion being
absolutely tight. The amount of leakage, while insignificant, was, until
remedied, sufficient to spot the outside of the tower, making it
unsightly; and this, in the writer's opinion, is just what would have
happened had the tank been constructed in the ordinary manner, with