MILITARY PYROTECHNY. 139 



effects and greatly to increase the danger of preparation. The most that 

 is done is to moisten the composition with oil of turpentine. The case 

 of the Congreve rocket is made of sheet iron, and in the pot incendiary 

 composition is placed ; the cap is made very strong, as the rocket is to 

 serve as a projectile at the same time. PL 40, Jig. 41, shows a Congreve 

 rocket, and it will be perceived that externally it differs but little from the 

 signal rocket ; it is, however, much larger, from two to three inches in dia- 

 meter. A, the rocket ; B, composition ; C, vault ; D, incendiary composition 

 with bursting-charge ; E, cap ; F F, choke-tie ; G, stick. Fig. 42 is a Congreve 

 rocket, as made at Vincennes, after Bem's method. B B is the rocket 

 proper, of sheet iron, with the composition ; B E, the choke-tie for the stick, 

 F ; C is the pot, filled with incendiary composition and pierced with holes ; 

 D, a barbed head on the cap, to hold the rocket fast when it strikes. Fig. 43 

 is a rocket after Congreve's last pattern. This is put upon the stick, C, by 

 means of a wrought-iron shoe, B, which carries the priming-vault, A 

 (fig. 45 shows this part in section, fig. 44, the lower view, where the six 

 holes are seen, through which the blaze of the composition streams out). 

 D is the rocket proper and E the pot, with the incendiary composition and the 

 flame holes running out into a sharp conical head. Fig. 46 shows the shoe, 

 B, with the screw for the priming-vault, A. The French Colonel Brulard 

 constructed the rocket now used in the French artillery, shown in fig. 47, 

 which represents the case. AB, BC, CD are three compositions of various 

 strength ; then follows a layer of clay, dba, through which a fuse,/, goes 

 into the pot of the rocket ; at a a the case is closed with strong iron plate. 

 Fig. 49 shows the outer view of the case ; fig. 48, the pot, having a burst- 

 ing-charge in the centre, which, kindled by th^fuse / (fig. 47), bursts the 

 pot and hurls around its loading of hand-grenades and musket-balls. To 

 make sure that the bursting-charge is set off, even if the rocket is by any 

 accident extinguished, and that it is lighted at the moment when the rocket 

 reaches its destination, the plan of setting it off by percussion has been 

 devised (fig. 50). In the iron case of the rocket, d, which has underneath, 

 in the bottom cc, several flame holes, e e, an iron plate, ik, is fixed at 

 top, at a b, and over the plate a cylindrical pot, containing a hand-grenade 

 and bursting-charge, is securely screwed. The pot itself has three flame- 

 holes in the part towards A. A is a box of cast iron, which is fastened to the 

 rocket-case and loaded with a bursting-charge and incendiary composition. 

 At /i is a firing-rod, of iron, which stands upon a ball, n, of fulminating 

 mercury. The instant the rocket strikes any object, the rod h is driven 

 down upon the ball, causing it to explode, thus firing the whole charge of 

 the pot and producing the effect. Fig. 51 is the floor of the rocket with 

 the flame-holes. Fig. 52 is a Congreve rocket which is fired without stick, 

 the screw-thread wound around it on the outside being designed to give it 

 a regular motion of revolution and thus direct its flight. Fig. 53 is a Con- 

 greve rocket which scatters hand-grenades in its flight. R is the rocket 

 proper, whose floor at T T has flame-holes, and whose filling is at Z. U is 

 part of a case which is screwed on, serving instead of a stick, and in the 

 iron envelope of which small hand-grenades, V, are inserted, with a bursting- 



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