In the case of the capitol at Albany, N. Y., the soil was tested by applying a measured load to a square foot and also to a square yard. The machine used was a mast of timber 12 inches square, held vertical by guys, with a cross-frame to hold the weights. For the smaller area, a hole 3 feet deep was dug in the blue clay at the bottom of the foundation, the hole being 18 inches square at the top and 14 inches at the bottom. Small stakes were driven into the ground in line's radiating from the center of the hole, the tops being brought exactly to the same level; then any change in the surface of the ground adjacent to the hole could readily be detected and measured by means of a straight-edge. The foot of the mast was placed in the hole, and weights applied. No change in the surface of the adjacent ground was observed until the load reached 5.9 tons per sq. ft., when an uplift of the surrounding earth was noted in the form of a ring with an irregularly rounded surface, the contents of which, above the previous surface, measured 0.09 cubic feet. Similar experiments
were made by applying the load to a square yard with essentially the same results. The several loads were allowed to remain for some time, and the settlements observed.* Similar experiments were made in connection with the construc tion of the Congressional Library Building, Washington, D. C., with a frame which rested upon 4 foot-plates each a foot square. The frame could be moved from place to place on wheels, and the test was applied at a number of places.
Tests have been made of the soil under a river bed by forcing a 3-inch closed pipe into the ground by hydraulic pressure.t 655. In interpreting the results of tests of bearing power, the fact should not be overlooked that a small area will bear a larger load per unit of area for a short time than a larger area perpetually; and hence, the area tested should be as large as practicable and the test should continue as long as possible.