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To Charge Rocket Cases

In charging rocket cases, in order to increase the rapidity of its discharge a wire is sometimes inserted through the centre of the charge, the rammer being constructed with a small bore through its length, to receive this wire when ramming the charge. This wire is withdrawn when the charge is complete, and yrotechny. This is the art of making fireworks. The three principal materials employed in this art are charcoal, saltpetre, and sulphur, combined with filings of the space it has left is filled with a quick iron, steel, copper or zinc, or with resin, cam- match (see No. 2060), which thus sets fire to phor, lycopodium and other substances, to the entire charge at once. This central space impart color, or to modify the effect and dura- is called the soul of the rocket, and the adoption of the combustion. Gunpowder is used, tion of this arrangement is necessary for either in grain, half crushed, or meal (finely large rockets, especially those having heavy ground), as circumstances may require. Iron pots. filings give red and bright spots. Copper 2053. Το Choke Firework Cases. A filings give a greenish tint to flame; those of short cylindrical piece of wood, of the same diameter as the thin end of the rod used for rolling a case, is furnished with a wire, the thickness of which must be the same as the desired bore of the choke. The end of the A B N C rod has a hole bored in it to receive this wire loosely. A is the rod on which the case is to be rolled; C the cap of the same diameter as the end of the rod, having the wire inserted firmly in its axis. The rod is bored, as the dotted lines at B denote, to receive the wire.

The outside dotted lines indicate a case on the rod, choked at N. This is effected by stretching a piece of strong cord, a single turn of which is passed round the case at N, compressing it firmly and leaving a bore of the same size as the wire between the rod and the cap. In rolling a case to be choked, the paper should be used in pieces, each piece