Page:Miscellaneous Papers on Mechanical Subjects.djvu/170



69. A Four-masted Clipper Ship.—A large clipper ship of 4,000 tons was being built at Boston; the length of keel was 287 feet, length on deck 320 feet, extreme breadth of beam 52 feet, and depth of hold 30 feet. Her keel is of rock maple in two thicknesses, the frame is of seasoned white oak, dowelled, and bolted together through the dowelling with 1 inch iron. The frame inside is diagonally crossbraced with iron, the braces being 4 inches wide, and ¾ inch thick, bolted through every timber: these braces extend from the floor-heads to the top timbers, and form a perfect network of iron over all her frames fore and aft.

She has five depths of midship keelsons, each 16 inches square, three tier of sister keelsons, 15 inches square, bolted vertically and horizontally. There are four tiers of bilge keelsons on each side, 15 inches square. Ceiling, from bilge to lower deck 15 inches, scarped and bolted edgewise.

She has three full decks, securely fastened with fore and aft knees; the hanging knees are extra fastened, having in the lower hanging knees 18 bolts, 1¼ inch iron; middle deck, 20 bolts; also upper deck hanging knees, 20 bolts, and all of oak. Beams in lower deck, 14 by 16; in middle deck, 15 by 17; in upper deck, 12 by 16, and some 12 by 20 inches.