PYROTECHNY. 



Pvrotech- not sufficient to introduce any error into a computa- 

 n 7- tion formed on this basis, greater than those which 

 ""v-^ would arise from an actual measurement of the vertical 

 ascents. 



On the Firing of Rockets. 



On the There are various modes of firing rockets when in- 



firing of tended for purposes of amusement or ornament, but 

 rockets. we shall first consider the discharging of single ones, 

 whether used with that view, or as intended for sig- 

 nals. So much in the performance of a rocket, whe- 

 ther in the altitude of its ascent or the verticality of 

 its direction, depends on the care used in firing, that 

 it is impossible to be too particular on this point, as 

 the very best made ones may fail for want of proper at- 

 tention to many minute points. 



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 port-fire 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 beau- 

 ty of the performance when for amusement, and so 

 important 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 ; because not only the object may be defeated, 

 but the rigging endangered ; an accident that might 

 prove serious should there be any sail set, as the can- 

 vass 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 port-fires, 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 port-fire. 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 con- 

 sequence 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 illumina- 

 tions 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 can enjoy. 



Such flights may vary from 100 to 1000 and up- 

 wards, and they are extremely striking when great 



3 



numbers are fixed together. That they may fire toge- Pyrotcch- 

 ther, however, it is necessary that they should be re- ny. 

 gularly primed with quick-match in the same manner. ^ -V"-" 

 The bit of match being introduced into each, and pro- 

 perly 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 port-fire. 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 uncom- 

 mon to place the stick in a musket barrel, and to dis- 

 charge them from that. But this also is an imperfect 

 method. It is impossible to place the musket in a per- 

 pendicular 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. 



The same kind of simple stand answers the purpose,, 

 also, on shore, when rockets are fired for amusement. 

 But as, in most of those cases.there are commonly crowds 

 of people collected, who might be endangered by the 

 falling of the sticks, it is necessary to throw the rockets 

 so far off from the perpendicular as to avoid all hazard 

 of their falling back into the crowd when they are 

 burnt out. In the same way, the engineer may choose 

 some piece of ground where they may fall with the 

 least injury, avoiding houses, or places where there 

 may be corn or hay or other combustibles, and choos- 

 ing a piece of open meadow ground or other naked 

 land. By knowing the altitude of ascent, it is very 

 easy to compute the necessary inclination for this pur. 

 pose, without, at the same time, causing the rocket to 



