138 MLITARY SCIENCES. 



d. Signal Rockets. To communicate signals at great distances rockets 

 are employed, which are made of various dimensions. Th'e largest of these, 

 having the calibre of a one-pound iron ball, mount to the height of 5,500 ii. 

 The rocket composition consists of a mixture of meal powder and charcoal, 

 which is rammed in such a manner into a case made up of paper rolled 

 together and pasted, that a central cavity is left through the whole length. 

 To make the rocket case, sheets of paper (a one-pound rocket requires about 

 sixteen sheets of writing-paper) are rolled upon an exactly calibred vy^ooden 

 staff, the " former ;" then, at a short distance from the end, broken in and 

 choked (pL 40, Jig. 8, at h), so that there still remains an opening into the 

 case, the fuse-hole, and then tied. To fill this case with composition a 

 rocket-mould is used (Jig. 31, section) ; this consists of a foot, a, with the 

 neck a', upon which is the knob and spindle d, by which the bore of the 

 rocket is formed. The mould proper, b b, is fastened to the neck by means of 

 the pin e. In this mould the case is placed, and driven by means of the former 

 a (Jig. 32, section) upon the spindle, so that the hollow b, of the former, cc^ 

 receives the spindle, whereupon a light blow is given with the mallet {Jig. 

 37), forcing the case down upon the knob, and forming the vault {C,Jlg. 41). 

 Then some composition is poured in, and rammed firm with the rammer a 

 (Jig. 33), the hollow of which, b, receives the spindle. As the case fills 

 higher and higher, rammers are used with a shorter cavity (Jigs. 34 and 35) 

 and lastly the solid rammer (Jig. 36), with which a short part, the solid por- 

 tion, is driven. When the rocket is so far completed, it is taken from the 

 mould (Jig. 38, a, rocket ; h, choke ; b, solid part), and at / a somewhat 

 larger chamber, i, placed upon it, in which some grain powder (the bursting 

 charge) and a light-ball, are put, and the whole then terminated by the 

 pointed cap, g. Such a rocket is now fastened to the stick k (Jig. 39), by 

 the ties h and h', that it may mount in a straight line. This stick is seven 

 times the length of the case, with which it must, when balanced a few 

 inches from the mouth, be in equilibrium ; a is the rocket, i the pot, g the 

 cap. In the vault is placed the priming for lighting the charge, and the 

 rocket, with the mouth free, is then hung upon a nail. If the rocket is not 

 to throw a fire-ball, but only to make a report, then a petard is placed in 

 the pot. This is made strongly of tin plate, and filled with powder. If the 

 light signal is to fall slowly, it is furnished with a parachute (Jig. 40). In 

 the pot is then placed a tin fight box, a, bored with holes, and provided with 

 the four small wires, cc cc, to which the parachute is fastened, all this 

 being placed in the pointed cap, and unfolded by the explosion. 



e. CoNGREVE Rockets. Great attention has been attracted, for a long 

 time, to the rockets invented by the English Colonel Congreve, with which 

 powerful effects were attained, although they have, perhaps, been somewhat 

 exaggerated. For a length of time they were kept secret, but are now 

 introduced into almost all artillery. The composition consists of saltpetre, 

 sulphur, and meal powder, in various proportions, according to the size of 

 the rocket. The largest have 20 parts saltpetre to 1 part sulphur and 

 1 meal powder. Many other substances, such as chlorate, &c., formerly 

 added, are now laid aside, having been found to produce but insignificant 



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