turning at the pier head.

[Illustration: PLATE XXX.--YACHT PIER NEAR GLEN COVE, N. Y.]

Comparative designs and estimates were prepared for (_a_) a pier of
ordinary construction, but with creosoted piles; (_b_) a concrete pier
on concrete piles; and (_c_) for a series of concrete piers with wooden
bridge connections. The latter plan was very much the best in
appearance, and the calculated cost was less than that of the pier of
concrete piles, and only slightly more than that of creosoted piles, the
latter being only of a temporary nature in any case, as it has been
found that the protection afforded by creosote against the teredo is not
permanent.

At this point on the Sound the mean range of the tide is about 8 ft.,
and it was determined that at least 5 ft. above mean high water would be
required to make the underside of the dock safe from wave action. There
is a northeast exposure, with a long reach across the Sound, and the
seas at times become quite heavy. These considerations, together with 4
ft. of water at low tide and from 2 to 3 ft. of toe-hold in the beach,
required the outer caissons to be at least 20 ft. high.

To construct such piers in the ordinary manner behind coffer-dams, and
in such an exposed location, was to involve expenditure far beyond that
which the owner cared to incur. The writer's attention had shortly
before been called to the successful use of reinforced concrete caissons
on the Great Lakes for breakwater construction, by Major W. V. Judson,
M. Am. Soc. C. E., and under patents held by that officer. It seemed
that here was a solution of the problem. These caissons are constructed
on the shore, preferably immediately adjoining the work. After thorough
inspection and seasoning, they are usually launched in a manner somewhat
similar to a boat, are towed into position, sunk in place, and then
filled with rip-rap.

In this case what was needed was a structure that could be constructed
safely and cheaply in the air, could then be allowed to harden
thoroughly, and could finally be placed in accurate position. The
weights to be supported were not great, the beach was good gravel and
sand, fairly level, and, under favorable circumstances of good weather,
the placing of the caissons promised to be a simple matter. Therefore,
detailed plans were prepared for this structure.

An effort was made to preserve some element of the yachting idea in the
design, and bow-string trusses, being merely enla