n body of the beach by
slue-ways. The Coast Surrey has been notified of the matter, and the
assistant to whom I have already referred has visited the Hook, and made
an informal report, which agrees essentially with the statements of
Colonel Delafield. A complete and reliable report can only be made upon
_actual surveys_; and we trust these will be executed, and the
Government placed in possession of the whole truth.

We understand that Colonel Delafield has already, upon a small scale,
made some very successful experiments of curvilineal dikes, constructed
with caissons of concrete; and we have no doubt that, with adequate
means at his disposal, this ingenious engineer could avert the dangers
which threaten, not only the fort, but the noble harbor of New York.

To return to the Physical Survey, and to speak as briefly as we may upon
so extended a subject, we hold that it is possible, by a patient
collection of facts and figures, to determine the natural _scheme_ of
the harbor--we had almost said the _formula of its development_.

It is ascertained that the group of shoals which form the Bar--composed,
as they are, for the most part, of loose and shifting sands--are not
accidental accumulations, modified by violent storms and freshets, but
that they are orderly arrangements, made by the currents, to whose
unceasing activities are due the form and preservation of each bank and
channel. The peculiar contours of the shoals given by our most ancient
charts are still developed by recent surveys, although alterations in
magnitude have taken place. _The order of the physical forces is
unchanged, but their work is still progressing._

Now, since these currents have determinable laws, regulating their
periods, durations, velocities, and directions, it was only necessary to
compile observations, in order to reduce this study to a simple
consideration of the _composition of forces_.

'The process by which sand is swept along by currents upon the bottom of
the sea, is not unlike the motion of dunes upon the land; a ridge of
sand is propagated in the direction of the current by the continual
rolling of the particles from the rear to the front. This movement is
exceedingly slow when compared with that of the current which induces
it, and for this reason a shoal, though traversed by violent tidal
currents, may, as a whole, remain stationary when the alternate drifts
are equal and opposite; for in this case, though the sand upon the