Pontons

A kind of portable boats specially adapted for the formation of floating bridges required by armies. They are constructed in various ways, of wood, metal, or prepared canvas, stretched over frames made for the purpose (the latter it is said are much in favor), and have the nece ary gear placed with them for transport. The ponton used in the U. S. army is constructed as follows: The ponton frame is composed of two side frames, of twelve narrow and of two wide transoms. The former are strengthened at the ends by iron straps, which are countersunk and perfectly smooth; all the edges of the frame and transoms are well rounded to prevent chafing the canvas. The wide transoms are of 10-inch by 1 1 ⁄ 2 -inch plank, provided with tenons to fit the mortises in the frame. The narrow transoms are of 4-inch by 2 1 ⁄ 2 -inch scantling. The articles of each of the above cla es are made exactly alike, so that they may be interchanged. Two of the narrow transoms are provided with an iron mooring becket. The frame when a embled is held together by a rope pa ed through the rings in the ends of the side frame, and tightened with a rack-stick. The ponton cover is of 0000 cotton duck, double-seamed, with the border double for 1 1 ⁄ 2 inches in width. The clew-line eyelets are of metal. The lashings are of 1-inch rope 18 feet in length, and looped at one end, and the cable used is of 3-inch Manilla rope, 30 fathoms long.