These are large paper cylinders, filled with powder, Stars, Sparks, &c. They are generally made of paste-board, and about four diameters long; they should be choaked at one end like common cases. They are generally exhibited in numbers, fixed on a plank of some kind, in the following manner: on the under side of your plank, make as many grooves as you intend to have rows of pots, then at a little distance from each other, and exactly over the grooves, fix as many pegs, about three fourths or one diameter high; then through the centre of each peg bore a hole down to the groove at bottom, and on every peg fix and glue a pot, the mouth of which must fit tight on the peg; then through all the holes run a quick-match, one end of which must go into the pot, and the other into the groove, which must have a match laid in it from end to end, and covered with paper, so that when lighted at one end it may discharge the whole almost instantaneously. In each pot put about one ounce of mealed and corn powder; then in some put Stars, and in others Rain, Snakes, Serpents, Crackers, Sparks, &c. When they are loaded, secure their mouths by putting paper over each.
When fired in considerable numbers, these Pots des Brins, from their affording so great a variety of fires, produce a most pleasing exhibition.
Jets of Fire.
4. Jets of Fire.
These are a kind of fixed Rocket, the effect of which is to throw up into the air Jets of Fire, similar in some respects to those produced by water. If a number of such Rockets be placed horizontally on the same line, it may be easily seen that the fire they emit, will nearly resemble a sheet of water, arranging itself in the form of a cascade. When the Rockets are arranged in a circular form, like the radii and periphery of a circle, they form what is termed a fixed Sun.
To procure these Jets of Fire, the cartridge for brilliant fires must in thickness be equal to a fourth part of the diameter, and for Chinese Fires only a sixth part of the same.
The cartridge must be loaded on a nipple, having a point equal in length to the same diameter, and in thickness equal to a fourth part of it; but, from the effect of the fire, the mouth generally becomes larger than is requisite; but this may be prevented, by charging the cartridge after the manner of the Chinese, who fill it to a height equal to a fourth part of the diameter with clay; this must be rammed down as if it were gunpowder.
When the charge is completed with the composition you have made choice of, the cartridge must be closed with a tompion of wood, above which it must be choaked.
The train or match must be of the same composition as that employed for loading; otherwise the dilatation of the air, contained in the hole made by the piercer, would cause the Jet to burst.
Clayed Rockets may be pierced with two holes near the neck, in order to have three Jets on the same plan.