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 Eng. Societies.
For sticking paper to zinc, use starch paste with which a little Venice turpentine has been incorporated, or else use a dilute solution of white gelatine or isinglass.
CENTRIFUGAL PUMPS AT MARE ISLAND NAVY YARD, CALIFORNIA.[1]
By H.R. CORNELIUS.
In December, 1883, bids were asked for by the United States government on pumping machinery, to remove the water from a dry dock for vessels of large size.