The mass of concrete beneath the old foundation is 126 feet 6 inches square, 13 feet 6 inches in depth, and extends 18 feet within the outer edge of the old foundation and 23 feet 3 inches beyond this line. In placing this work, 70 per cent of the area of the earth upon which the Monument was standing was removed. The second part of the strengthening of the foundation consisted in constructing a continuous buttress beneath the shaft and extending out upon the concrete slab, so as to distribute the pressure over the foundation. In this operation sections of the rubble masonry were removed and replaced with concrete. As compared with the original bulk of the old foundation, 51 per cent of its contents was removed and 48 per cent of the area of the base of the shaft undermined. The new foundation rests on a bearing surface 126 feet 6 inches square, or 16,002 square feet, as compared with 6,400 square feet for the old foundation. The entire work of underpinning was accomplished without causing the slightest crack or the least opening in any joint of that portion of the Monument already constructed, which, including the foundation, was 80 feet square at its base. The new foundation rests upon a bed of fine sand 2 feet in thickness, below which is a bed of bowlders and gravel. Borings were made in this deposit for a depth of 18 feet without passing through it. Thus, as completed, the new foundation covers two and a half times as much area and extends 13¹⁄₂ feet deeper than the old one, being 36 feet 10 inches in depth. The bottom of the work is only 2 feet above the level of high tide in the Potomac. No settlement has occurred to date. [Illustration: THE WASHINGTON MONUMENT AS SEEN FROM THE MALL GROUNDS]