flats.

"When a work like this subserves the double purpose of military defence
in times of war, and of promoting the interests of commerce between
several of the States of the Union in time of peace, it would seem to
have an increased claim to the attention of the General Government. If
any work of improvement can be considered national in its character,
the improvement of St. Clair flats, in the manner proposed, may, it is
submitted, justly claim to be placed in that category."

The plan proposed by the United States Engineers for this improvement is
to construct two parallel piers of about four thousand feet long, as a
permanent protection to the channel-way, and to dredge out a channel
between these piers, six hundred feet wide and twelve feet deep. The
cost of this work is estimated at about $533,000. This may seem a large
sum of money; but when it is considered that the value of the commerce
which passed over these flats in the year 1855 was ascertained by
Col. Graham to be over two hundred and fifty millions of dollars, or
considerably more than the whole exports of the Southern States for the
year 1860, more than a million of dollars per day during the period of
navigation, and that the increased charge on freights by reason of this
obstruction is more than two millions of dollars per annum, which of
course has to be paid by the producer, the investment of one quarter of
that annual charge in a work which would do away with the tax might seem
to be a measure of economy.

To show the importance of these lake-harbors, and the vast amount of
commerce which depends upon them, and which has grown up within the last
twenty years, we will give an extract from another of Col. Graham's very
interesting Reports, upon the Chicago harbor.