The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1885-10-09
THE DAVIS ISLAND DAM.
Something About the Great Work Which Is
Expected to Make a Harbor for Pittsburg.

ooAhOthAAE <ADoue tA0 Urcat "oTA sshACA 40
Expected to Make Harbor for Pittsburg.
Pittshurg Letter.
Seven years ago. this month, work was COM
menced upon the Davis Island DAM" Delays
in securing appropriations from Congress, TO-
gether with numerous floods have caused a loss
OF fully three years time, the latter adding
greatly to the cost which now represents a total
of 100000 while under favorable circum-
stances it is claimed that the same work could
have been done for some $500 900 less.
The construction was under the charge of
Colonel Merrill, of the United States government
engineering corps from plans made under his
supervision, and embraces the same features as
contained in the dams built by the government
on Kanawha river, in Virginia. The lock and
gates are Colonel Merril's own plans, while the
dam is patterned after the French system of
movable wckets.
From the wall of the lock to Davis island is the
dam proper there is short dam between the
island ard the opposite shore) distance of l, 223
feet. 1t is divided into four parts or sections,-
the nayigaole pass of $50 feet Immediately next
to the lock, and two weirs of 224 and ZIG feet,
spectvely. The divisions are marked by stone
piers short distance above the dam.
The dam is composed of a line of wickets, 303
in number, four feet in width by twelve feet in
height, made Of six-nch timbers firmly bOlted
together, covered with heavy plank ard are
connected with concrete foundation by an iron
frame not unlike the letter H, with journals
both where the frame is connected with the
wicket and the foundation At the former place
a wrought-iron bar or prop twelve feet long, and
weighing over 900 pounds extends to long
iron guide, (securely fastened to the foundation)
but is only fastened to the wicket
The guide plate is the patent Of Frenchman
who has made large claim for royalty-and
by its use does away with much umbersome
machinery that otherwise would be necessary for
operating the dam successfully.
1t consists OF a long iron plate with an angle
In abont the center is shoulder, against which
the prop rests when the wickets are raised; run
ming alonside of the shoulder and next to the
angle of the plate is guide for the prop to run
in when being lowered, and extending along the
plate back of the shoulder is a guide so con-
structed that the prop adjusts itself when
raised.
The support of the wicket is fastened to this
plate about the center, and when the wicket is
grappled by the aid of boat constructed for the
purpose, it is lifted while remaining in fat
position, assisted by its natural buoyancy
Upon reaching the height of its supporter, the
latter and tine prop assume the shape of an irreg-
ular letter A. When TINS occurs, the prop be-
comes adjusted to the shoulder or the socket in
the guide plate, and as the current strikes the
end OF the wicket II careens to its position, and
four feet of the dam is in place This operation
proceeds until the entire dam is raised.
AS the wickers are only four feet wide EACH
the pressure of the water not SO great but they
can be easily handled.
In case of high water the dam is to be lowered
and this is accomplished by pulling the wickets
back about ten inches allowing the prop to
move past the shoulder of the guide plate and
the whole sinks to the bottom.
This is done in the navigable pass from the
boat and from surface bridge extending from
the piers in the weirs. This bridge can be
lowered to the bottom of the river, Also leaving
with the exception of the three piers, an unob-
structed channel in high water.
The lock is 600 feet in length and ITO feet in
width inside measurement. and is intended to
receive an entire feet of coal boats and steamer
without any readjustment, as is necessary at all
the other locks upon the river.
The gates massive affairs, containing each
over 40. 900 feet of lumber and &C. 900 pounds of
iron, and are stiffened by what is commonly
known as the Howe railroad truss, lying upon
its side The gates are drawn into recess walls
by hydraulic power supplied from tanks, holding
5000 gallons, at an elevation of sixty feet to
six-inch turbine wheels placed in the wall at the
shore end of the gates. 1t is believed that the
lock can be made ready to either receive or dis
charge fleet in from six to eight minutes.
Across the head of the lock on the outside of
the gate are placed twenty seven wickets, to be
raised when repairs are necessary, thus doing
away with costly cofferdam etc.
1t is a somewhat remarkable fact that of all
the hands employed but one serious accident has
occurred In the seven years-through direct dis
obedience of orders one man was drowned.