At 13 feet distance for firing at 30 degrees. 21 feet ” ” ” at 20 30 feet ” ” ” at 15 40 feet ” ” ” at 10 over an epaulment of 8 feet high. See also the word _Battery_. _POINT BLANK._—For the point blank ranges of different pieces of ordnance, see the different natures. The French _point blank_ or _but en blanc_, is what the English artillery call the _line of metal elevation_; in most guns between one and two degrees. _PONTOONS._—Length at { top 21 ft. 6 in. { bottom, 17 2 Width, 4 feet 9 inches. Depth, 2 feet 3 inches. _Equipage of One Pontoon._ Ft. In. Ft. In. In. 4 Baulks 22 8 long 1 0 wide 4 thick. 1 Gang-board. 22 0 ” 1 0 ” 2½ ” 6 Chesses, 11 6 ” 2 4 ” 1½ ” 2 Oars. 1 Anchor. 1 Graplin. 1 Setter. 4 Iron bolts, with keys. 2 Mounting bars. 4 Binding sticks. 4 Spring lines. 4 Faukes. 1 Cable 1 Sheer-line. 1 Boat hook. 1 Maul. 4 Pickets. 1 Small pump. 1 Windlass. 1 Pontoon carriage, complete. _Dimensions of Colonel Congreve’s Wooden Pontoons._ feet. inches. Length at top 26 ” at bottom 23 Depth 2 8 Width 2 3 The common pontoons will support a weight of 4 or 5000 pounds. They are generally placed, in forming a bridge, about their own width asunder. See the word _Bridge_. _PORTFIRES._ Composition. Saltpetre, 60 parts; sulphur, 40 parts; mealed powder, 20 parts. Length of each, 16½ inches. One will burn from 12 to 15 minutes. Weight of one dozen, 3 lbs. 12 oz. Portfires were made at Gibraltar in the following manner; two ounces of nitre was dissolved in a gallon of water, and sheets of soft brown paper dipped in the solution: these when dry were rolled up to about the size of common portfires. _PROVISIONS._—See the word _Ration_. _PROOF_—of ordnance. All natures of ordnance undergo several kinds of proof before they are received into his Majesty’s service; _viz._ 1st, They are guaged as to their several dimensions, internal and external, as to the justness of the position of the bore, the chamber, the vent, the trunnions, _&c._ 2d, They are fired with a regulated charge of powder and shot, and afterwards searched to discover irregularities or holes produced by the firing. 3d, By means, of engines an endeavour is made to force water through them; and, 4th, They are examined internally, by means of light reflected from a mirror.