Work was resumed on the shaft in 1880. The first 13 courses--26 feet--were faced with white marble from Massachusetts. The remainder is Maryland white marble similar to that used in the lower section. The new work was backed with dressed New England granite to the 452-foot elevation, above which the walls are entirely of marble, of through-and-through blocks, and from the 470-foot level, where the ribs of the pyramidion begin, the courses are secured to each other by mortise and tenon joints cut in the builds and beds of the stone. During the working season of 1880, 26 feet were added to the shaft; in 1881 there were added 74 feet; in 1882, 90 feet; in 1883, 70 feet; in 1884, 90 feet. These additions brought the walls of the shaft to a height of 500 feet on August 9, 1884. The pyramidion topping the shaft is supported on 12 marble ribs, which spring from the interior faces of the walls of the well, beginning at the 470-foot level. The covering slabs are 7 inches in thickness and are supported upon projections or spurs on the marble ribs. The pyramidion has a vertical height of 55 feet 5¹⁄₈ inches and consists of 262 separate stones. The weight of the pyramidion is 300 tons. The capstone, which weighs 3,300 pounds, was set in place on December 6, 1884. Over it is a small pyramid of pure aluminum 5.6 inches at its base, 8.9 inches high, and weighs 100 ounces, the largest piece of this metal ever cast in any country to that time. The following inscriptions appear on the four faces of the aluminum capstone: JOINT COMMISSION AT SETTING OF CAPSTONE: CHESTER A. ARTHUR, M. E. BELL, EDWARD CLARK, JOHN NEWTON, ACT OF AUGUST 2, 1876. CORNER STONE LAID ON BED OF FOUNDATION JULY 4, 1848. FIRST STONE AT HEIGHT OF 152 FEET LAID AUGUST 7, 1880. CAPSTONE SET DECEMBER 6, 1884. CHIEF ENGINEER AND ARCHITECT, COL. THOMAS LINCOLN CASEY, CORPS OF ENGINEERS. ASSISTANTS: GEORGE W. DAVIS, CAPTAIN FOURTEENTH INFANTRY; BERNARD GREEN, CIVIL ENGINEER; MASTER MECHANIC, P. H. MCLAUGHLIN. LAUS DEO.