PROCEEDINGS OF THE POLYTECENIC ASSOCIATION. 



443 



throug-h the knob of the cascabel, like the screw on the naval boat-howitzer, 

 and in dismounting- the gun it is necessary to depress the muzzle until the 

 foot of the screw slides back to the enlargement of the slot, shown on this 



a-- - -^ ^ \ plan view of the piece bolted on the top of the trail, 

 ■: : ^ into which the foot of the elevating screw works, and 



during which it moves as the gun is elevated or depressed, until the button 

 on the bottom end will rise through the enlargement of the slot. Either 

 gun can be mounted on the same carriage, and can be elevated 35° for 

 any service requiring it. Each gun weighs 725 pounds. The gun and 

 carriage weigh 1,850 pounds, and the recoil is but twenty inches. 



By the great elevation that can be attained on the guns, shot can be 

 projected along a high trajectory'', falling nearly perpendicularly. With 

 one ounce of powder in the rifled gun with 35" elevation, the range is 800 

 yards; with two ounces, 1,200 yards. Fuse shells can thus be dropped 

 into otherwise inaccessible places — inside earth-works or forts — or shot can 

 be projected over a mountain with either gun, so elevated, and take effect 

 in a valley beyond. With a full charge of powder at this elevation, a shell 

 can be projected more than four miles, to burn barracks or buildings, 

 bridges, etc., or to annoy an enemy. The range of shell from the smooth- 

 bore gun is also considerable, with the great elevation at which, if neces- 

 sary, it can be used. The guns are no less effective at short range from 

 these modifications. 



The slotted and curved piece which supports the elevating screw allows 

 it to be tapped through the cascabel of the gun, so as to prevent the guu 

 from jolting and hammering upon the elevating screw. 



THE SIGHTS. 



The cuts exhibit the sights employed to facilitate the directing of the 

 gun, and may be applied to both forms of the guns. The side figures are a 



front view and a cross section of the front sight, and mode of mounting the 

 same. The middle figure is a side elevation of a portion of a gun with 

 sights. A is the breech and B the cascabel of the gun. C is the elevating 

 screw, and Z) is a rear sight, which is mounted in wa3's E, to be traversed 

 right and left by turning the screw F. The ways E and their attachments 

 are supported by a rod G, which is adapted to slide vertically through 

 the neck K. His & piece of metal fixed upon the breech A, at the point 

 represented, and provided with a hole, exactly in line with the hole in the 



