MILITARY ENGINES. 119 



position, as a base moulding, &c. The form of a truncated cone is also 

 given to guns {jig. 3). Behind the first reinforce the gun receives a rein- 

 forcement which is called the cascable, with its knob and neck, the latter 

 serving to facilitate the handling of the gun. PL 36 shows the different 

 cannon of the principal powers, arranged according to their calibres, and 

 the scale which is annexed gives the means of learning all the details of the 

 ordinary construction. Fig. 2 shows a Bavarian 3-pounder. Of 6-pounders, 

 the Saxon is shown in Jig. 3 ; the Prussian, Jig. 4t ; the Austrian, Jig. 5 ; 

 the Russian, Jig. 6 ; the French, Jig. 7 ; the English, Jig. 8. Fig. 9 is a 

 Spanish 8-pounder ; Jig. 10, a French. Fig. 11a Prussian, and Jig. 12 an 

 Austrian 12-pounder. Fig. 13 a short French, and Jig. 14 a Russian 24- 

 pounder. And of the balls, Jig. 38 shows a 24, Jig. 39 a 12, Jig. 40 an 8, 

 and^^. 41 a 6-pound ball. 



The weight of guns is usually in the proportion of 150 pounds to each 

 pound of ball for light, and 200 pounds for heavy guns, with a charge of 

 from ^ to I the weight of the ball. Field guns are from 16 to 21 calibres 

 in length, siege and garrison guns as much as 24 calibres. 



Near the end of the bore is placed the vent (Jig. 14/), sometimes perpendi- 

 cular, sometimes oblique to the axis. The base-astragal (or ring) and muzzle 

 give the points of direction, by means of which the gun, which is movable 

 upon the trunnions in the carriage, can be brought in line with the object 

 aimed at. As the thickness of metal is materially less at the muzzle than 

 at the breech, the moulding on the muzzle, or swell of the muzzle, is of con- 

 siderable height, and upon it a small knob of metal (the dispart) is fixed, in 

 line with a notch cut in the base-ring, and at such a level, that, when this 

 knob, the notch on the ring, and the point of aim are in the same line, the 

 shot will, at a certain known distance, 800 paces, for example, for 6-pounders, 

 exactly hit the point aimed at. For greater distances a greater eleva- 

 tion must, of course, be taken, i. e. the breech-sight must be depressed 

 with respect to the dispart, the degrees of variance from a due level 

 being regulated by means of a movable piece (Jig. 32) set upon the 

 base-ring. This is cut out at be to fit the ring, and pierced with holes at 

 every quarter of an inch. The scale ad shows the distances to which the 

 holes correspond, so that by looking through the proper hole and bringing 

 the dispart (fore sight) in line with it and the object, the ball will strike at 

 the distance required. More recently this hausse (movable sight) has been 

 let in to the base-ring (Jig. 33) and the breech-sight set upon it, so that by 

 sliding up the stem of the hausse according to the distance, for a 6-pounder 

 at 1000 paces one inch for instance, and there clamping it by means of a 

 screw, aim can be taken more conveniently than when it merely stands 

 loose upon the base-ring. The piece is discharged by applying the match 

 to the vent, yet fire-locks have been applied (pi. S6,Jig. 34), with cock a, 

 and battery b, and in modern times percussion-locks. Both are sprung by 

 means of a cord. 



An uncommon species of gun is shown at Jig. 1, viz. the 1-pounder cannon 

 of Bernay, a newly invented hand-gun which requires no carriage. Upon 

 a light stand, 6, rests the lever, d g, which serves for handling the gun 



595 



