1 Keelson. 2 Floor timbers. 3 Naval timbers or ground futtocks. 4 Lower futtocks. 5 Middle futtocks. 6 Upper futtocks. 7 Top timbers. 8 Half timbers, or half top-timbers. PLATE IV. EXPLANATIONS. SHIP.--A ship is square-rigged throughout; that is, she has tops, and carries square sails on all three of her masts. BARK.--A bark is square-rigged at her fore and main masts, and differs from a ship in having no top, and carrying only fore-and-aft sails at her mizzenmast. BRIG.--A full-rigged brig is square-rigged at both her masts. HERMAPHRODITE BRIG.--An hermaphrodite brig is square-rigged at her foremast; but has no top, and only fore-and-aft sails at her main mast. TOPSAIL SCHOONER.--A topsail schooner has no tops at her foremast, and is fore-and-aft rigged at her mainmast. She differs from an hermaphrodite brig in that she is not properly square-rigged at her foremast, having no top, and carrying a fore-and-aft foresail, in stead of a square foresail and a spencer. FORE-AND-AFT SCHOONER.--A fore-and-aft schooner is fore-and-aft rigged throughout, differing from a topsail schooner in that the latter carries small square sails aloft at the fore. SLOOP.--A sloop has one mast, fore-and-aft rigged. HERMAPHRODITE BRIGS sometimes carry small square sails aloft at the main; in which case they are called BRIGANTINES, and differ from a FULL-RIGGED BRIG in that they have no top at the mainmast, and carry a fore-and-aft mainsail instead of a square mainsail and trysail. Some TOPSAIL SCHOONERS carry small square sails aloft at the main as well as the fore; being in other respects fore-and-aft rigged. They are then called MAIN TOPSAIL SCHOONERS. [Illustration: Plate IV. Ship Bark Full-rigged Brig Hermaphrodite Brig Top-sail Schooner Fore & aft Schooner Sloop] PART I. CHAPTER I. GENERAL RULES AND OBSERVATIONS. Construction of vessels. Tonnage and carriage of merchant vessels. Proportions of the spars. Placing the masts. Size of anchors and cables. Lead-lines. Log-line. Ballast and lading. CONSTRUCTION OF VESSELS.--As merchant vessels of the larger class are now built in the United States, the extreme length of deck, from the after part of the stern-post to the fore part of the stem, is from four and a half to four and three fourths that of the beam, at its widest part. The Damascus, of 700 tons' measurement, built at Boston in 1839, and considered a fair specimen of our best freighting vessels, had 150 feet from stem to stern-post, and 32 feet 6 inches extreme breadth. The Rajah, of 530 tons, built at Boston in 1837, had 140 feet length, and 30 feet beam;--being each in length about four and six tenths their beam. A great contrast to this proportion is exhibited in the most recent statistics (1841) of vessels of the same tonnage in the English navy; as the following table will show.