MILITARY PYROTECIINY. 135 



the core ; c, the jet hole ; e e, the key-bolts for locking the mould ; and /, 

 key-bolt for the core-spindle. 



3. Military Pyrotechny. 



The manufacture of cartridges of all kinds, and of fireworks generally, 

 especially of fire and light balls and rockets for military purposes, is the 

 object of a particular art, that of Military Pyrotechny, the basis of which is, 

 of course, the manufacture of gunpowder, since from this, in its various 

 forms and with different additions, the above named articles are all pro- 

 duced. 



a. Gunpowder. Gunpowder is a mixture of sulphur, saltpetre, and char- 

 coal. The roll-sulphur is pulverized, and the saltpetre likewise. The char- 

 coal, from soft but not gummy woods (linden, alder, poplar, &c.), is also 

 powdered fine by a particular apparatus. The proportion of the ingredients 

 is various ; a medium (Prussian military powder) is 75 parts saltpetre, 12^ 

 sulphur, and 12j- charcoal. The materials are first mixed dry. This is 

 done in a mixing barrel, hh, divided by partitions, I [pi. 40, fig. 5, cross- 

 section, ^g*. 6, longitudinal section), which is turned by the crank a, and set 

 on the inside with laths, c ; the trap d serves to fill and empty it. The 

 material when well mixed is brought to the mill, which is either a rolling or 

 stamping-mill. The latter is the most simple ;j^^. 1 gives a Yiew, fig. 2 the 

 section of one. In a block, D, the pots or pits G G G are hollowed out, in 

 which the lower surface is made of hard heart wood, and which are nar- 

 rower above than below, so that the stuff continually falls back upon itself. 

 In each of these run two stamps, E E, shod with bronze, which are lifted 

 alternately by cams, a, on the cylinder A, lying on the frame F, which cylinder 

 is set in motion by some power applied to the cog-wheels B and C. The 

 rolling-mill (fig. 3, side view, ^^. 4, upper view) has a marble bed-stone, A, on 

 which rests the bed, a, for the vertical shaft B, of which b is the upper bed, 

 and which is turned by the bevel-wheels Q, on the shaft S, working into the 

 bevel-wheel P. This vertical shaft carries the runner-axle D, which by an 

 arrangement at d can be set higher or lower, and on this revolves the mar- 

 ble runner, E E, which by means of the wedge arrangement dd, and the 

 plates t and a;, is pressed against the end, m, of the axle, and runs round with 

 it. The standing shaft carries at the same time the two frames F and G for 

 lifting and dropping the three crutches, H, I, K, which serve to bring the 

 material constantly from the centre and edge under the path of the runner. 

 The lever arrangement, L, whose point of support is at c, raises or lowers 

 the supports m for K, i for J, and /)/> and q for H. N is the border (curb) 

 of the bed-stone ; M, a trap for removing the finished material from the 

 stone by means of the curved crutch, H. The well mingled mass is moist- 

 ened with water, brought to one or the other of these mills, and then more 

 intimately and perfectly mixed and worked together. Thus mixed it is 

 taken to the plate-mill (fig. 7), where it is converted into cakes of one 

 and a half to two lines in thickness. In the frame A lie the rollers B 

 (turned by means of the cog-wheels D and I), E, and F, connected by an 



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