The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1872-06-10

| Ihe Destruction of the Middle Ground
Our readers win be glad to learn that there is
promise that within the next thirty days the
work of dredging ship canal through the
Middle Ground will be finished, and the I'M
pleasant obstacle to the entrance and departure
of heavy tonnage except at high water will be
overcome. 1t is the only Objectionable thing
about our harbor, and when it is fully removed
the way from the ocean to any of our wharves
will be open and clear to the largest merchant
vessels a1oat. 1t opens a channel 1850 feet
long, and 500 feet wide, with 20 to % feet of
water at low tide. Lying as this shoal does,
nearly abreast of the Grand Trunk wharyes,
which are used in winter by the Allan line of
steamers, it was difficulty in the way of their
business, and the line has continually in
creased the size of its vessels, and our Ameri-
can merchant marine is made up of larger yes
sells than formerly, it became evident years
ago that some measures must be taken to re-
move the shoal or as much of it as obstrueted
navigation. Under an appropriation of Con-
gress contract was made with Messrs. H. B.
Cooley & Co, of Philadelphia in 1868 They
began work in August with an Otis dredger,
but the contractors found the bottom of a diff
ferent nature from what they anticipated, and
that the machine was not fitted for the work.
In February, 1859, Augustus r. Wright took
the Messrs. Cooley & Co. S contract and finish
ed it in May following. Later in the season
contract for further prosecution of the work
was made with Messrs. Morris & Cummings of
New York, two of the heaviest contractors for
this sort of work in the country. They complet-
I'D +Jair in H.
was then suspended for about year for want
of an appropriation, and also to give new con-
tractors time to prepare themselves with i'm
proved machinery Messrs. Curtis & Fobes of
this city next undertook the job and on the 18th
of last September they began operations with
new and expensive apparatus; and the work
has been prosecuted with slight interruptions
ever since. The engineers in charge tell us that
they find three strata in the bottom of the shoal
first stratum of deposit, soft and yielding
and incapable of sustaining weight-evidently
vegetable formation. This varied in depth
from two to six feet, Beneath this is strata
of blue slay, very heavy and tenacious, free
from sand and having greasy feeling" Water
appears to have no effect upon it; it is almost
insoluble, and nearly as heavy as granite,
weighing about 100 pounds to the cubic foot.
Beneath this is layer of stiff yellow clay,
which dries out almost white and is quite fri
able. This is found at depth of twenty -four
feet below low water-mark. Occasionally a
seam of sand of exceeding fineness is reached.
The Otis machine, which operates by "a scoop,
could do comparatively little in bed of This
clay, and the progress was! slow. The present
contractors use a dredge built by the Portland
Company 1t is driven by double engine of
100-horse power, working 'clam-shelP' scoop
in two parts with strong teeth or fingers
These are driven into the bottom and closed to-
gether and will bring up three cubic yards at
time. About 500 yards day are taken out on
an average, each working day, though as high
as 1000 yards have been removed on several oc-
casions. The earth is full of marine life and
some curious specimens have been preserved for
the study of naturalists. The work of cutting
this channel is under the management of Gen.
Thorn, U. s. Engineers. Mr. ILeProhon, an ac-
eomplshed engineer has direct supervision of
the operations The task once done the cham
mel promises to be permanent Critical obser-
vations have been made by the gentlemen in
charge, of the effect of the tide upon it. The
increased depth of water has given greater
securing power to the tides, which will keep
the cut clean Some changes in the direction
of the current are observed, the effect of which
will be favorable to navigation rather than
detrimental hz rH