234 



Pyrotech- cover large spaces, consolidate all into one great mass, 

 "y- and are very economical in saving many burning fire- 

 "V-" 1 " works. 



For these the pyrotechnist must depend chiefly on 

 the painter ; particularly when emblematical figures 

 are introduced, or where architecture is to be repre- 

 sented. In works on this scale, the great mass of the 

 firework consists of transparent painting, and the burn- 

 ing fires are only its ornaments, to be lighted and re- 

 newed in various parts of the building in succession, 

 so as to keep up the effect for a great length of time. 

 All these paintings are executed on stout white linen, 

 such as that used for window blinds, if on a large scale, 

 and with the same kinds of oil-colour diluted, with tur- 

 pentine the whole being rendered transparent where 

 necessary by a coating of drying oil or varnish, and 

 darkened where required by means of black paint. 

 These paintings must be properly stretched on separate 

 frames, so thaf they may be kept tight, and easily re- 

 placed, and taken away from the greater frame- work 

 to which they are attached. 



In smaller transparencies, particularly where they 

 are not likely to be wanted again, or where only some 

 temporary inscription or emblem is necessary, paper 

 may be used ; but it must be strong enough, and pro- 

 perly secured by means of strings stretched tight 

 across it. In certain kinds of wheels, represent- 

 ing suns and stars, transparencies may be turned to 

 great account by using more than one, and commu- 

 nicating motion to them by means of the revolving 

 machinery. Thus, for example, if one transparency, 

 formed by bright rays, is covered by another behind, 

 so calculated by its colouring as to intercept the light 

 'by fits while it is revolving, many splendid effects can 

 be produced. In the same manner, two or more such 

 circular transparencies may be made to revolve in dif- 

 ferent directions ; while, being painted with different 

 colours, a great variety of showy appearances may be 

 caused at a very cheap rate. But we have not room 

 to give designs or farther descriptions of these con- 

 trivances ; while we may refer for them to books in 

 every one's hands, viz. Hooper, or Hutton's Recrea- 

 tions. 



As the light of lamps is not sufficiently brilliant and 

 powerful for firework illuminations of this nature, it is 

 necessary to use the burning compounds, such as the 

 zinc light and the antimonial light. The effects may 

 also in this way be varied by adopting different colours, 

 and may be maintained as long as is requisite, by dis- 

 posing so many behind the transparency, that one may 

 take fire before the other is quite extinguished. 



Of Timeing Fireworks. 



Of timsing Every thing, in the compound fireworks, whether 

 fireworks, burning together or in succession, depends on accuracy 

 in the length of their action, and in the precision with 

 which the various parts begin, end, and follow each 

 other. Even in the simplest, a defect in this respect 

 is very disagreeable to the eye ; and, in illuminations, 

 the ornamental appearance is very much injured, unless 

 the lights all expire nearly at the same time. In the 

 same manner, it is absolutely necessary that one work 

 should be completely exhausted before another begins, 

 wherever there are mutations ; and that no interval of 

 darkness should take place between them. All these 

 objects are to be obtained only by great care in the 

 different parts, in the composition, the driving, the 

 lengths of cases, and the priming, the quality, and the 

 fixing of the different leaders. 



PYROTECHNY. 



Under, the head of compositions, we have already 

 pointed out the way in which these are to be managed 

 for this purpose ; so that we need now say nothing 

 more on that subject. In filling, or driving, great care 

 and many attentions are necessary ; as it is here in par- 

 ticular that the fireworks are apt to become unequal, 

 and thus to go wrong. The measure by which the 

 composition is to be introduced should, in the first 

 place, be a cylinder, and not a shovel, as is commonly 

 the case, as it can always be filled more accurately each 

 time ; so that the charge to be driven shall be always 

 equal. Each diameter of case should also have its own 

 measure ; and these should all be numbered to corre- 

 spond with the moulds, by which means all chances of 

 errors from this cause are avoided. In driving, the 

 same mallet should be used for each size of case, and 

 these should also have corresponding numbers. The 

 workmen should also be careful always to give the 

 same number of blows ; and this being regulated for 

 each class of cases, from sixteen upwards to sixty, the 

 habit of doing it steadily is easily acquired. But in all 

 larger works, a pile engine, furnished with a tell-tale 

 to keep the account, is the only method to be depended 

 on. 



Where there is no such machine, all the cases that 

 are intended to burn together should, as much as pos- 

 sible, be driven by the same individual ; and as the 

 chief artist can number each man's work, he may class 

 the cases accordingly ; so as to adopt those, of the 

 length of burning of which he is accurately informed. 

 For all things else he must depend on such calcula- 

 tions as he may choose to make respecting the perform- 

 ance of his pieces. But a sample of each kind should 

 be tried, and the time of burning measured by the se- 

 cond's pendulum, when it should be marked on each 

 case; that so when the works come to be put toge- 

 ther, the operator may be quite sure of what he is do- 

 ing, and be able to balance and arrange them accord- 

 ingly. That accurate time is really attainable in this 

 way, is very certain ; because in military works,. out 

 of a thousand fuses perhaps, where the time is most 

 important, since the bursting and effect of a shell are 

 entirely regulated by it, it will be found that not a se- 

 cond of difference takes place. 



With respect to leaders, it is only necessary that 

 they should act as quickly as possible, since no time 

 is allowed for these ; and that point is to be ensured 

 by good quick-match, and careful priming and fitting. 



Of Skyrockets. 



We have chosen to treat of this kind of firework Of sky- 

 first, not only on account of its beauty, and its univer- rockets, 

 sal use in all cases, but because, in detailing the mi- 

 nute attentions which it peculiarly requires, it will be 

 less necessary to dwell on that subject in describing 

 the construction of others. The same precautions and 

 proceedings in every respect, if in a less degree, are 

 required for all sorts of driven cases, whatever their 

 objects may be. 



We have, in our table of compositions, given a va- 

 riety of those which may be used for sky-rockets, but 

 shall here name that one which is best adapted for 

 those of a pound weight, where the original materials, 

 and not mealed powder, are used. This consists of 

 nitre 4 lb., sulphur 1 lb., and charcoal 1| lb. The me- 

 thod of making the cases, and the construction of the 

 moulds and rammers, having already been described, 

 it is unnecessary to notice them again. 



The measure used in introducing the composition 



