platform was sunk
to the head of the piles by the increasing weight of masonry.

The center pier is octagonal, and is built in the same general manner
as to foundations as the shore piers, but the piles are cut off 22
feet below water, and there are eighteen courses of timber in the
grillage. The diameter of the platform between parallel sides is 53
feet, while that of the lower course of battered masonry is but 37
feet. The areas are as 2,332 to 1,147, or as 2 to 1 nearly. The
pressure per square inch of timber on the heads of the piles is about
the same as stated above for the shore piers. The number of piles
under the center pier is 483.

The risks and delays by this method of constructing the foundations
were much less, and the cost also, than if an ordinary coffer dam had
been used. Also the total weight of the piers is much less, as that
portion below a point about two feet below the water adds nothing to
their weight.

The piles were driven with a Cram steam hammer weighing two tons, in a
frame weighing also two tons. The iron frame rests directly upon the
head of the pile and goes down with it. The fall of the hammer is
about 40 inches before striking the pile. The total penetration of the
piles into the clay averaged 27 feet. The settlement of the pile
during the final strokes of the hammer varied from one quarter to
three quarters of an inch per blow.

There are 122 masonry pedestals, of which eight are large and heavy,
carrying spans of considerable length. They will all be built upon
concrete beds, except a few near the river on the north side, where
piles are required.

The four abutments with their retaining walls are of first-class
rock-faced masonry. The footing courses are stepped out liberally, so
as to present an unusually large bottom surface. They rest on beds of
concrete 4 feet thick. The foundation pits are about 50 feet below the
top of the bluffs, and are in a material common to the Cleveland
plateau, a mixture of blue sand and clay, with some water. The
estimated load of masonry on the earth at the bottom of the concrete
is one and seven tenths tons to the square foot. Two of the large
abutments were completed last season. They show an average settlement
of three eighths of an inch since the lower footing courses were laid.

The facts and figures here given regarding the viaduct were kindly
furnished by the city civil engineer, C.G. Force, who has the work in
charge.--_Jour. Asso. of E