232 



PYROTECHNY. 



Pyrotech- In the next place, the flaming and the sparkling 

 n y- lights may be combined in an endless variety of ways, 

 ^y^^ The very same case may alternately throw out both 

 the kinds of fire. Or the angles of a sparkling tri- 

 angle, or of a square, or else the centres of these 

 figures, may be occupied by coloured stars, or their 

 sides may be dotted with such lights; or alternations 

 of figures of lights with figures of sparkling fire may 

 be adopted. Thus, for example, the centre of a sun 

 may be filled with a blaze of lights, while its margin 

 radiates with sparks ; or else it may commence with 

 one species, and terminate with another. But, for the 

 same reasons, we need not attempt to describe varie- 

 ties which only become more numerous as they be- 

 come more complicated. We must refer to th'e plates, 

 and to our future examples, for a few such specimens 

 as may serve to illustrate this part of the subject, trust- 

 ing to the artist's ingenuity for conceiving farther 

 what we may not find room to describe. 



The varieties of moving fireworks is much greater 

 than that of fixed, abstractedly considered ; yet these 

 are not susceptible of so many distinct and compli- 

 cated combinations. As the most simple case, we may 

 mention that of burning bodies projected into the air 

 by explosions, such as stars, serpents, &c. whether out 

 of rockets, or shells, or from Roman candles. The 

 sky-rocket is the chief of those which act by their 

 own force of recoil, and the varieties of which it is 

 susceptible will be described when we come to treat 

 of that firework. On a similar principle, line rockets 

 and water rockets produce their particular effects : the 

 principle of recoil being modified by the particular 

 kind of restraint to which they are subjected. In the 

 tourbillon, the recoil of a wheel, or that of revolution, 

 is combined with that of motion in a straight line, 

 and thus the very striking effects of this simple fire- 

 work are produced. 



But the most various effects of recoil in fireworks 

 are produced, by restraining that force within circles, 

 and hence arises the great varieties of wheel movements. 

 The spiral, or pin wheel, is a familiar, but not the most 

 simple case of circular recoil. By suspending a simple 

 cylinder on a pin passing transversely through its own 

 centre, and using lateral instead of direct apertures, a 

 revolving recoil is caused, and hence arises a circle of 

 fire or a wheel. But in works of this nature, which 

 are required to burn longer, it becomes necessary to 

 form larger circles than can be produced from one case. 

 Thus many of these are disposed round the margin of a 

 wheel, or, what is the same thing, on radii proceeding 

 from a centre, suspended on an axle in the same man- 

 ner as a carriage wheel. This is the common Cathe- 

 rine wheel as it is called ; and according to the desired 

 length of time in burning, the cases may consist of any 

 number from two upwards, the effects being altered in 

 appearance by placing these at greater or less distances 

 from the centre. At very small distances, and with 

 great velocity, a continuous circle of fire may be pro- 

 duced ; at much larger ones, the form described by this 

 is of a very different nature. 



The simple circular recoil may be modified as to its 

 effects, by disposing the fireworks in an angle not co- 

 inciding with the plane of the wheel, or radii, on which 

 they are to revolve. Thus the effort is much diminish- 

 ed according to the resolution of forces, but the figure 

 of the fire becomes entirely different. Such wheels as 

 this are commonly disposed on vertical instead of ho- 

 rizontal axes ; and they are susceptible of still further 

 changes of appearance, by alternately reversing the 



mouths of the fireworks, so that the stream of fire may Pyrotech- 

 be directed in an alternating manner obliquely up- ry< 

 wards and downwards. ^^V"* 1 



Combinations of circular recoil motions are also ma- 

 naged so as to produce very entertaining eff -cts. Thus 

 if the radii of the larger wheel are caused to carry small- 

 er ones, it is plain that a very compound path of light 

 will be produced by the latter, resembling exactly that 

 path which the moon performs round the earth ; the 

 principal circle including smaller ones, which move 

 forwards along an orbit concentric to the first. Other 

 simple combinations of single wheels are also easy; but 

 we shall only here further mention, that in which two, 

 either of different 'sizes or the same, are caused to re- 

 volve in opposite directions in a common centre. The 

 effects of these movements are very lively and bril- 

 liant. 



As in all such simple wheels the power is sufficient 

 to carry a considerable weight round, if the centres be 

 carefully made, it is easy to attach to different parts of 

 them burning fireworks of different kinds, which have 

 not in themselves any moving force ; notwithstanding 

 which, they can be made to produce circles as if they 

 , had a power of their own. Thus also, either the cases 

 of the wheels themselves, or others connected with the 

 movement, may be caused to project stars ; and in this 

 way also varieties are produced. 



As we need not, however, enter now into any more of 

 these general details respecting the attainable variety in 

 simple combinations, we must proceed to notice the 

 general principles on which the more complicated fire- 

 works of these kinds are made. In these, different 

 kinds of the simpler forms, or of the first order of com- 

 binations, are caused to act in succession, or together ; 

 and thus the further we proceed in combining, the more 

 numerous do the varieties become. Thus moveable 

 and fixed works of all kinds may be united to an ex 

 tent which is only limited by the size, and weight, and 

 bulk of the machinery, and by the expence. A very 

 few hints on the most general parts of this subject may 

 be useful. 



If a complicated succession consists of fixed pieces 

 only, they may be so managed as to fire each other, 

 without any further intervention of the operator than 

 the first lighting. This is done by a proper disposi- 

 tion of the leaders, on which the operator must calcu- 

 late according to his views. The communicating lead- 

 er, of course, extends from the end of that which has 

 been burnt out, to the commencement of the one that 

 is intended to follow. If many and distant ones, as in 

 the case of extensive groups of illuminating lights, are 

 to be fired so as to burn together, it may become requi- 

 site to have more leaders than one from the same point 

 to different ones, otherwise such works may light in a 

 slow succession instead of simultaneously ; in conse- 

 quence of which, not only the first effect will be un- 

 pleasant, but the terminations will be more so, as they 

 will die out in succession, instead of expiring altogether. 

 Such leaders must be so firmly fixed, a? to insure them 

 against being displaced by any explosion from the 

 works that have burnt out ; and in cases of large and 

 expensive complications, it is prudent to have a spare 

 conductor, known to the operator, so that he may be 

 able to light it by means of his port-fire, should the ex- 

 pected communication fail. In very complicated ma- 

 chines, such as architectural fireworks of great extent, 

 it becomes impossible to produce, or unsafe to trust, 

 the communications to a continuous set of leaders ; and 

 proper ones must therefore be provided in different 



