The method of priming them is the first thing to be considered. If rockets are under the pound size, it is unnecessary to be curious about priming, or even to prime at all. They may be lighted at once, even without breaking the paper bottom, by means of the portfire. But it is not prudent to follow this practice with the larger dimensions. If the portfire is held too long at the vent-hole, which may easily happen, the flame may spread suddenly so far up into the bore, as to produce a slight explosion. It is not often that a rocket will burst from this cause; but it may be so far shaken out of its place on the post, as to take a wrong direction on going off, and thus the perpendi cularity of its flight, reckoned so essential to the beauty of the performance, when for amusement, and so im portant in the case of signals, may be disturbed. It is particularly necessary to be cautious in this point, when signal rockets are used on board of a ship ; be cause not only the object may be defeated, but the rig ging endangered ; an accident that might prove serious should there be any sail set, as the canvass might easily be fired.
It is, therefore, always prudent to prime the larger rockets. This is to be done by means of a piece of quick-match introduced into the vent; but, for the same reason as in the use of portfires, it must not be pushed beyond an inch upwards into the bore, where it may be steadied by a little bit of tow. In the same way it must be fastened to the stick, close to the vent, that it may not drop out, and the tail of it may then hang loose for the engineer's portfire. When the weather is doubtful, or, indeed, in all cases, it is pru dent to enclose the quick-match in a paper tube. This may further be secured within the mouth of the rocket, by pasting some paper round the whole, so that every thing is secured from any accident, in consequence of sparks or carelessness. In wet weather, it must be painted after being thus primed, and, in this way, no disappointment can follow.
Rockets are often discharged in flights, particularly in fireworks on a very large scale, where they are dis tributed in various places about the buildings, so as to relieve the spectators' attention among the illumi nations and figured movements, and to rouse it when about to flag. In cases of great rejoicings, when large crowds of the lower orders are present, so as to prevent each other from seeing straight forward, flights of rockets are particularly necessary, as it is often the only part of the spectacle which many of them -an enjoy.
Such flights may vary from 100 to 1000 and up• awl they are extremely striking when great numbers are fixed together. That they may fire to gether, however, it is necessary that they should be regularly primed with quick-match in the same man ner. The bit of match being introduced into each, and
properly secured to the sticks, the whole of the tails are to be collected and made fast to a common leader, to which the engineer applies the portfire. Sometimes they are fired by strewing powder under them on the frame. But this practice is not safe ; because some of them may miss fire, while others burst; and, in any case, their lines of ascent will be disturbed and irre gular.
To return to the simple case, and suppose that the single rocket is primed and ready for firing, it is pro per to describe the mode in which it is to be disposed, for flight upon the support. Very small ones may be held in the hand, by means of the stick, and let go in this manner ; but it is impossible to insure a vertical ascent by this method. On board of ships, it is not un common to place the stick in a musket barrel, and to discharge them from that. But this also is an imper fect method. It is impossible to place the musket in a perpendicular position, or to retain it in one ; besides which, if the stick is long, as it is in the one pound signal rockets, and the case heavy, the former bends, in consequence of its elasticity, so as not only to throw the rocket off the perpendicular, but to make its direc tion uncertain, as it wavers about from side to side be fore it is fired. In this way, also, the weight of the case serves to bend the stick in such a manner as to make it adhere to the muzzle of the piece during its oscilla tions, by which accident the flight may be materially retarded, as well as disturbed ; while the people near it are also annoyed by its fire before it starts.
On board of a ship, the best place for discharging the signal rockets is near the poop, on the quarter or stern railing, to which a perpendicular spar should be lashed for the purpose. Two round nails, driven in near the top, may serve for the rocket to rest on ; these being just wide enough to suffer the mouth to hang freely upon them, so as to leave plenty of room for the stick. Two pairs of similar nails, placed at proper distances below, will serve as guides to the stick till the rocket is clear of the post, and has acquired its proper direc tion. But it is much better to have a pole properly fitted for this purpose, by means of smooth round loops, fixed at proper distances, through which the stick is to be passed. The pole should also be set up as near the perpendicular as possible, by means of a plummet, which may be tried upon it when erected. A musket bullet and a string will answer all the requisite pur poses. These precautions are all very necessary ; partly to insure a good flight, and partly to avoid the chance of the rockets interfering with the rigging.