These are generally made of one-ounce serpent cases, seven or eight inches long filled two-thirds with charge, and the remainder bounced. The common method of firing them is this: Take a water-wheel, with a tin mortar in its centre, which load with squibs after the usual method; but the powder in the mortar must be no more than will throw the squibs out easily into the water. The cases may be placed on the wheel, either obliquely or horizontally, and on the top of the wheel, round the mortar, fix two cases of brilliant fire perpendicularly to the wheel. These cases must be fired at the beginning of the last case of the wheel, and the mortar at the conclusion of the same.
Sec. IX. Of the Water Fire-Fountain.
A float made of wood, three feet in diameter is to be provided. In the middle, a perpendicular post, four feet high and two inches wide must be inserted. Three circular wheels, made of thin wood, but without spokes, are fixed round this post. The largest of these wheels must be placed within two or three inches of the float, and must be nearly of the same diameter. The second must be 2 feet 2 inches in diameter, and fixed at the distance of two feet from the first. The third wheel must be 1 foot 4 inches in diameter, and fixed within six inches of the top of the post.
The wheels being arranged, take 18 four or eight-ounce cases of brilliant fire, and place them round the first wheel, with their mouths outwards, and inclining downwards. On the second wheel, place thirteen cases of the same, and in the same manner as those on the first. On the third, place eight more of these cases, in the same manner as before, and on the top of the post, fix a gerbe. Then clothe all the cases with leaders, so that they and the gerbe may take fire at the same time. The float should be tried first in the water, to see if the fountain stands upright.
Sec. X. Of Swans and Ducks, to discharge Rockets in Water.
This experiment may be made, by forming swans, or ducks of paper, leaving a cavity within. They are to be filled with small water-rockets, with some blowing powder to throw them out. Having made and painted some swans, fix them on floats. Then in the place where their eyes should be, bore holes two inches deep, inclining downwards, and wide enough to receive a small port-fire. The port-fire case for this purpose must be made of brass, two inches long, and filled with a slow bright charge. In the middle of one of these cases, make a little hole. Then put the port-fire in the eye-hole of the swan, leaving about half an inch to project out, and in the other eye, put another port-fire, with a hole made in it. Then, in the neck of the swan, within two inches of one of its eyes, bore a hole slantwise, to meet that in the port-fire. In this hole, put a leader, and carry it to a water-rocket, that must be fixed upon its tail, with its mouth upwards. On the top of the head, place 2 one-ounce cases, four inches long each, driven with brilliant fire. One of these cases must incline forwards, and the other backwards. They must be lighted at the same time as the water-rocket; to do which, bore a hole between them in the top of the swan's head, down to the hole in the port fire, to which carry a leader. If the swan is filled with rockets, they must be fired by a pipe from the end of the water-rocket, under the tail. When the swan is put in the water, the two eyes are to be lighted.
Sec. XI. Of Discharging Rockets under Water.
Stands must be made as usual, only the rails must be placed flat instead of edgewise, and have holes in them for the rocket sticks to go through; for if they were hung upon hooks, the motion of the water would throw them off. The stands being made, if the pond is deep enough, sink them at the sides so deep, that, when the rockets are in, their heads may just appear above the surface of the water. To the mouth of each rocket fix a leader, which must be put through the hole with the stick. Then a little above the water must be a board, supported by the stand, and placed along one side of the rockets; and the ends of the leaders are to be turned up through holes made in this board, exactly opposite the rockets. By this means, they may be fired singly, or at once. Rockets may be fired by this method in the middle of a pond, by a Neptune, a swan, or a water-wheel.
A rocket, which is fired in the water, and, after burning there half the time of its duration, mounts into the air with great velocity, may be thus constructed. Take a sky-rocket, furnished with a rod, and, by means of a little glue, attach it to a water-rocket, but only at the middle, in such a manner, that the latter will have its neck uppermost. Adjust to their extremity, a small tube, to communicate fire from the one to the other, and cover both with a coating of wax, pitch, &c. that they may not be damaged by the water. Then attach to the sky-rocket, after it has been thus cemented to the aquatic rocket, a rod, and, by means of a string, support a musket bullet, made fast to the rod by means of a needle or piece of iron. When these arrangements have been made, set fire to the match after the rocket is in the water, and, when the composition is in part consumed, the fire will be communicated through the small tube to the other rocket. The latter will then rise and leave the other, which will not be able to follow it, on account of the weight adhering to it.
Sec. XII. Of the Representation of Neptune in his Chariot.