Barker's hydraulic machine, described in Gregory's Mechanics, which is put in motion by two opposite currents of water, acting from the two extremities of an oblong box, supported by a perpendicular hollow shaft, through which the water first passes, acts upon the same principle as this revolving sun. The ascension of rockets is also to be accounted for in the same way. See [General Theory of Fire-works.]
The whirling serpents are charged entirely with composition. No grain powder is used. A small paper stopper is rammed on the top of the composition. Near the two chokes, but in opposite sides, the cases are pierced with small holes, which are made to communicate with each other, and with the composition, by means of a short leader or match.
Sec. VI. Of Chinese Flyers.
Somewhat similar to whirling serpents are the Chinese flyers. Cases for flyers may be made of different sizes, from one to eight ounces. They are formed of thick paper, and are eight interior diameters long. They are rolled in the same manner as tourbillons, with a straight pasted edge, and pinched close at one end.
The case, being put in a mould, whose cylinder, or foot, must be flat at top, without a nipple, is to be filled within half a diameter of the middle. Then ram in half a diameter of clay, and, on that, as much composition as before; and again put in half a diameter of clay. Pinch the case then close, and drive it down flat, and afterwards bore a hole exactly through the centre of the clay in the middle. In opposite sides, at both ends, make a vent, and, in that side, intended to be fired first, a small hole to the composition, near the clay in the middle, from which carry a quickmatch, covered with a single paper, to the vent at the other end. Then, when the charge is burnt on one side, it will, by means of the quickmatch, communicate to the charge on the other, which may be of a different sort.
The flyers being thus prepared, put an iron pin, that must be fixed in the work, in which they are to be fired, and on which they are to run, through the hole in the middle. On the end of this pin, must be a nut to secure it. If they are required to turn back again, after they are burnt, make both the vents at the ends in the same side, which will alter its course the contrary way.
These flyers are intended to revolve on an axis, and to discharge at different periods. For this purpose, a communication is made from one vent to the other. It is evident, that the clay, which occupies the middle of the case, is intended to prevent any communication of fire, in the tube, from one end to the other, as this is effected on the outside.
Sec. VII. Of Simple Stars.
The stars, which are not made upon the former, or roller, serve to furnish bombs and rockets. They are made in the following manner: The composition being well mixed, and passed through a fine sieve, is made into a paste, with gum arabic and brandy. The proportion of the gum to the composition, is as one to sixteen. The composition is spread equally on a table, about the thickness of a finger, and cut into small square pieces. They are then covered with meal-powder, which will serve for priming, and are dried in the shade.
Composition for Simple Stars.