Main-mast, two and a half times the ship's beam. Fore-mast, eight ninths of the main-mast. Mizzen-mast, five sixths of the main-mast. Bowsprit, two thirds of the main-mast. Topmasts, three fifths of the lower masts. Topgallant masts, one half the length of their topmasts. Jib-boom, the length of the bowsprit. Main-yard, twice the beam. Fore-yard, seven eighths of the main-yard. Maintopsail-yard, two thirds of the main-yard. Foretopsail-yard, two thirds of the fore-yard. Crossjack-yard, the length of the maintopsail-yard. Topgallant-yards, two thirds of the topsail-yards. Mizzentopsail-yard, the length of the maintopgallant-yard. Royal-yards, two thirds of the topgallant-yards. Spritsail-yard, five sixths of the foretopsail-yard. Spanker-boom, the length of the maintopsail-yard. Spanker-gaff, two thirds of the boom. For the thickness of the spars, the same book allows for the lower masts one inch and a quarter diameter at the partners, for every three feet of length; and nine tenths in the middle and two thirds under the hounds, for every inch at the partners. For the yards, one inch at the slings, and half an inch at the yard-arms, within the squares, for every four feet of the length. For the breadth of the maintop, one half of the beam, and of the foretop, eight ninths of the maintop. The following are the proportions of the spars of the ship Damascus, before mentioned, built in 1839. Main-mast 74 ft. Head 11 ft. 6 in. Size 26 in. Fore-mast 70 ft. Head 11 ft. 6 in. Size 25 in. Mizzen-mast 68 ft. Head 8 ft. 6 in. Size 18 in. Main and fore topmasts 41 ft. Head 6 ft. 6 in. Size 14-1/2 in. Mizzen topmast 32 ft. Head 5 ft. Size 9-1/2 in. Main topgallant-mast 23 ft. (15 ft. with 2 feet head.) Size 9-1/2 in. Fore topgallant-mast 21 ft. 14 ft. with 2 feet head.) Size 9-1/2 in. Mizzen topgallant-mast 17 ft. 11 ft. with 18 in. with 2 feet head.) Main and fore yards 60 ft. yard-arms 2 ft. 6 in. Main and fore topsail yards 48 ft. yard-arms 3 ft. 6 in. Main topgallant yard 37 ft. yard-arms 2 ft. Fore topgallant yard 34 ft. yard-arms 2 ft. Main royal yard 27 ft. yard-arms 1 ft. 6 in. Fore royal yard 24 ft. yard-arms 1 ft. 6 in. Main skysail yard 17 ft. Fore skysail yard 15 ft. Cross-jack yard 44 ft. yard-arms 2 ft. Mizzen topsail yard 35 ft. yard-arms 2 ft. 9 in. Mizzen topgallant yard 25 ft. yard-arms 1 ft. 6 in. Mizzen royal yard 16 ft. Mizzen skysail yard 10 ft. Bowsprit, out-board 27 ft. Size 26 in. Jib-boom 42 ft. Head 3 ft. Size 14-1/2 in. Flying jib-boom 40 ft. Head 3 ft. 6 in. Main pole 12 ft., 10 above royal-mast, 5 in. in cap.