Instead of choking the cases, plaster of paris is far preferable. Let it be 3⁄8 of an inch thick, and well dried, before charging. After the cases are charged, bore a hole through the plaster, 1⁄3 of a diameter, that is, with a 9⁄8 case, 3⁄8 of an inch diameter. For this purpose it is not necessary to have another shell-bit; bore it with the 3⁄16, and enlarge it with a penknife. It is better arched under, till conical, as shown in fig. 48. Prime with 4 or 5 pieces of match, and wash with the sash-tool.
The gerbe being finished, make a cylindrical box, or paper bag, of 2 or 3 thicknesses of paper: fill it with a number of crackers, and a scoopful of meal powder, and fasten it to the gerbe.
No single piece is more effective than a coloured gerbe; the stars will be projected 30 feet, or more: they may be put in, mixed; or, one layer may be blue, another green, another crimson. Twist a piece of wire, deprived of its elasticity, round the neck, and another piece round the bottom, and leave long ends; it can then be fastened by them to the top of a post. To remove the elasticity from iron wire, lay it in the fire till red hot; withdraw it with the tongs, and put it aside, to cool slowly. If copper wire is used, it will bend without preparation. String must not be employed, as it might burn, and let the case fall. Common pins, patent short whites, deprived of their elasticity, are useful for connecting the parts of lustres together.
[FLOWER POTS.]
These are choked cases, charged with spur fire: the fire is somewhat slow, so the cases must be short: 4 inches long, and 5⁄8 diameter is a good size. Rub the composition thoroughly up in the mortar; the vegetable black produces beautiful star-like sparks, totally dissimilar to any other. Put a little composition, at a time, into the case, and jolt it with the roman candle rammer.
Vegetable black, introduced into a star, causes it to tail, like linseed oil. Light such star on the hob; it will burn, and leave a residue, unaltered in shape; blow upon this continuously with the mouth, or, better still, with a pair of bellows: the supply of oxygen will cause it to boil up, in a state of fusion, when it will begin to throw out clusters of the peculiar starlike sparks, before mentioned, bright and yellow as new sovereigns.
Vegetable black is a pure lamp black; some samples of lamp black make equally good stars, but others are worthless. Greater reliance can be placed upon vegetable black. Vegetable black and lamp black must not be mixed with linseed oil, as such mixture is liable to spontaneous combustion.
Roll up a tube for pill boxes, of two thicknesses of brown paper. When dry, cut it into pieces about 11⁄8 inch long: choke one end, like a wheel case; set it on a nipple,and charge it with spur fire, till full within 1⁄16 of an inch: fill up flush with a little plaster of paris, pressed in flat with a knife: prime the choked end, and put a number of such cases into a rocket head, or shell.