Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

√15 × 64.3 = 31 feet per second nearly,

whence the weight

18000
31 = 581 lbs.

The form of the common pile-engine is too well known to need description.

Mr. Nasmyth’s system of pile-driving consists in forcing the pile into the ground by a great number of blows following each other in rapid succession. Piles were driven by his engine at the United States Dry Dock, at Brooklyn, (N. Y.,) as follows: A pile was sunk fifty-seven feet by a hammer of 4,500 lbs.; it was driven forty-two feet in seven minutes by three hundred and seventy-three blows.

MITCHELL’S SCREW PILE.

Mitchell’s screw pile is a cast-iron column, around the lower part of which is a spiral flange. It is screwed into the ground, and offers great resistance to vertical pressure, on account of the large bearing surface obtained.

DR. POTTS’S ATMOSPHERIC SYSTEM.

280. All methods of placing foundations in difficult positions must yield to the above plan, which consists in exhausting the air from a hollow cast-iron cylinder; when the pressure upon the surface of the ground, outside of the cylinder, forces the earth immediately under the pile to its interior; at the same time the pile sinks into the opening thus made, both by its weight and by the atmospheric pressure from the outside. The earth is moved from the interior of the pile; and when sunk to the necessary depth, the interior is filled with concrete.

A very successful application of the above system was made at the Goodwin Sands, at the mouth of the Thames River, (England). These sands change their position with every violent storm, and are yet so compact that a steel bar could be driven only eight feet with a sledge hammer; and a pointed rod three inches in diameter, when sunk thirteen feet deep, required forty-six blows from a one hundred lbs. ram falling ten feet to drive it one inch. But a hollow pile two and a half feet in diameter was sunk seventy-eight feet, at the rate of ten feet per hour for a part of the time. In case of meeting with rock, the pile may be converted into a diving-bell, and the obstruction moved.