PY RO TECH NY. 



2*7 



:CCLXXU 



. 3. 



Pig. 



On boring 

 fireworks. 





cases and rmi.ii-, ii i- UHIM < iv-sary to have any hollow 

 ran. m Her or lai than the dimensions 



at either extn-iue xvh'eh aie intended f.i-- the . '1 liti*, 

 ' wheel cases of less than a quar- 

 ter ill' a |>< uiid d'nieiix-'dus are commonly required, nor 

 re than two pounds, which tafcfe a rummer of 

 about one inch and live-tenths diameter, it is not ne- 

 cessary to be provided with any beyond thc->e two ex- 

 tremes. 



The description of the rammers required for driving 

 rockets will serve for that of all others, with so few al- 

 terations, that we shall first ment'on the construction 

 of thc-e, Plate ( ( ( ( I.XXI1. fig. 8, UV may a'-o a,- 

 . sume a uianu tcr of an neb, and a length of nine inches, 

 as all others may be reduced to this scale. In this, the 

 length of the composition *rom the choke is five inches 

 and a quarter, and tbecomp'ele ramrrer intended for it 

 must contain a conical cavity exactly fitted to the spin- 

 dle, fig. 1 2, which, for this length, is four inches long. 

 The diameter of this cavity or bore, at the bottom, is 

 half an inch, or, in all dimensions, half the diameter; 

 and it tapers regularly to the extremity, which is some- 

 what blunt. 



Now, as in driving, the rammer rises as the compo- 

 sition mounts up in the case, it is plain that, after a 

 short-time, the spindle will no longer reach the bottom 

 of the bore. Hence the composition accumulates in it, 

 and becomes hard driven on the top of the spindle, so 

 as to render it a matter of some trouble to clear it out 

 again. At the same time, as the rammer mounts up- 

 wards in the case, the protruded part becomes so long, 

 that it is difficult to give the same firm blows above, or 

 in the upper part of the composition, as were given in 

 the lower, in consequence of which the action of the 

 rocket becomes irregular. It becomes necessary, there- 

 fore, to have a succession of rammers for one rocket, 

 each, in turn, shorter than the preceding, and with a 

 shorter bore at the same time : the last and shortest is 

 to be quite so' ; d. A set of five is sufficier t ; but, if eco- 

 nomy is a great object, four may be made to answer the 

 purpose. 



For wheels, one bored rammer will be sufficient, as 

 the bores of these are not required to be long. It is 

 not always, indeed, that they require any boring ; and 

 in complicated movements of works, where it is possi- 

 ble to apply machinery to turn them, instead of trust- 

 ing to their own recoil alone, it is much better to do 

 so, as greater regularity is thus ensured. 



On Boring Fireworks. 



As the hollow rammers require occasional boring to 

 keep them clean, we may as well introduce the whole 

 subject of boring in this place, as there are some cases 

 in which it is indispensible. There is a peculiar ma- 

 chine sometimes used for this purpose by the makers 

 of fireworks, but no complicated contrivance is neces- 

 sary. For cleaning out the bores of the hollow ram- 

 mers, a drill moved by a drill-bow is quite sufficient ; 

 because the quantity of composition is so small, that if 

 it were to take fire it can do the operator no harm. 

 In metal rammers, it is fully more convenient to burn 

 it out by means of a bit of priming or quick match, or 

 else it may be washed out by soakjng in hot water, 

 though this method is somewhat tedious. Neither of 

 these methods, however, is applicable to wooden ram- 

 mers, for obvious reasons. 



In boring those single-case wheels which turn on a 

 hole in their o\v i centres, a common gimblet answers 

 every purpose, as it is barely necessary to perforate the 



paper. Small tourbillons may also be bored in the 

 same way ; but it is necessary that tallow be used with 

 the gi'nb'et, partly to mtke it work easily, and partly 

 to prevent the risk of taking fire. For large tourbil- 

 lons, however, the drill becomes necestary; as the la- 

 bour of boring these is very great, in consequence of 

 the hardness of the composition. These works cannot 

 be driven on spindles, on account of the complicated 

 directions of the bores. Hut the system of boring, 

 whether for rockets or large wheel-cases, ought to be 

 abandoned altogether in favour of driving on spindles. 

 The latter method is the snfe-t, and does not require 

 more time. It is quite possible for a work to take fire 

 under the drill, which may be attended with serious in- 

 conveniences ; betides which, there is danger that the 

 composition in a rocket may be disturbed, the conse- 

 quence of which would be for it to burst on fir: 

 We, therefore, recommend that drilling should be li- 

 mited to tourbillons, as we have already mentioned. 

 For this purpose nothing answers better than a com- 

 mon foot lathe, with the drill fixed in the chuck. If 

 the bore is to be made in the axis of the firework, that 

 may also be fixed fn the opposite one, and brought 

 gradually up by means of the screw ; but the tourbil- 

 lons require to be guided by the hand, as it is impos- 

 sible, by any methods of fixing them, to give a right 

 direction to the holes. Care must be taken that the 

 drills be kept well greased with tallow; and the drill- 

 ing-engine ought also to be out of doors, er in a sepa- 

 rate outhouse er tent. 



On the Moulds for Firenorlt. 



The moulds of fireworks, see fig. ], are the tubes in On the 

 which the cases are to be inclosed during the time of mouldi 

 filling, to prevent them either from bursting or sinking for fire ~ 

 downwards under the rammer during the time of driv- j* 01 " 1 "- 

 ing. They are absolutely indispensible in all works that CCCCLMU. 

 require driving, and can indeed only be dispensed with Fig. 1. 

 in spiral wheels. The general principles of the con- 

 struction are the same for all ; but as the rocket mould 

 is the most complicated, we shall first describe that 

 one ; the others will be easily understood. 



The rocket mould, if on a small scale, may be made 

 most conveniently of gun metal ; if large, of stout 

 wood, such as oak, elm, or, what is best of all, lignum 

 vitee. The upper part is a stout cylinder, generally 

 turned, with some ornamental moulding both above ard 

 below, so as to resemble a short column in architecture. 

 If in wood, it must be hooped at each end with a ring 

 of metal, properly secured by means of pins. The "bore 

 of this cylinder passes through it entirely, and is of the 

 exact diameter of the case which is to be driven. The 

 proportions of all these parts are regulated by those of 

 the rockets ; but we may here observe, that the length 

 of this cylinder, or of the bore which receives the case, 

 is about seven diameters. It may be more without in- 

 convenience, but cannot well be made less. If, on 

 putting the case- to it, that should prove too light, part 

 of the external paper is easily cut oft"; if otherwise, 

 a little more paper should be added, as it is essential 

 that the case should fill the mould perfectly. 



The lower part of the mould consists of a cylinder of 

 the same materials, but of nearly double the diameter, 

 or even more, that it may be enabled to stand firmly 

 on the block on which the work is driven. It is even 

 better, particularly in large works, that a cavity should 

 be made in the block to receive it, as we remarked some 

 time -ago, A krge cavity in which the upper cylinder 



