280 



PYROTECHNY. 



Pyrotech- glue, and the iron case is heated. When this done, 

 n >- the mandril with its paper cover on, is introduced 

 ""V^ into the case and rolled round, together with the lat- 

 ter. As the iron cools, the paper adheres to the case 

 and quits the mandril, which may then be withdrawn, 

 when the rocket is ready for filling. 



The moulds and rammers for filling the rockets must 

 be made strong and accurate, as it is most important 

 that all the work, in sizes so large, should be very true 

 and equable. The spindle on which the bore of the 

 rocket is to be formed, is made of gun-metal, and in the 

 form of a cone ; its base being equal to the dimensions 

 of the vent, and the length equal to two-thirds of that 

 of the rocket. It is slightly blunted at the apex. This 

 cone or spindle is fixed in a metallic nipple, or hemi- 

 sphere, which exactly fits the cup of the rocket, and 

 the whole is let firmly into a block of wood, which is 

 farther fitted to a deep hole in the larger solid block 

 beneath, that receives the whole force of the blows. 

 But in driving the charge, a collar of leather is put 

 on the nipple, so as to prevent the metal cup of the 

 rocket from coming into contact with it. 



The mould which is to contain the roc':et, to sup- 

 port it when driving, and to prevent it from splitting, 

 is made of two semi-cylinders of stout elm, which can 

 be put together and closed by means of hoops of gun- 

 metal. The outside of these blocks is accurately 

 squared, that this prism may fit the guides of the pile 

 driver, and it is let in below, after it has received the 

 rocket, upon the block which supports the nipple and 

 spindle, and which receives the whole work. Besides 

 this it is firmly fixed to the guides of the pile-driver 

 by loops and bolts ; and, in a similar manner, all the 

 other parts of the mould are studied so as to be ren- 

 dered one solid mass, capable of effectually resisting 

 the blows of the pile-engine. 



The rammers are made of ash, hooped at each end 

 with a well- fitted ring of gun-metal, and the whole 

 very truly and smoothly turned. It requires a set of 

 8 or 10 of these for each rocket, in proportion to its 

 size. The first has a hole in the axis, exactly capable 

 of receiving the whole spindle. In the next this hole 

 is less deep, and so on in succession till the last 

 is quite solid. The reason for thus changing them is, 

 to prevent the composition from getting into the holes, 

 which it would do as the filling of the rocket went on ; 

 so that at last it would be quite full of the composition 

 itself, and unfit to be used again without cleaning it 

 out. As it is, the composition does get into the fur- 

 ther end of the holes as the filling of the rocket pro- 

 ceeds ; and to clear it from this, it is convenient to have 

 a very small hole bored from the spindle hole quite 

 through the axis of the rammer ; by means of which 

 it is easily cleared. 



As it is most important that these rockets should be 

 not only hard driven, but uniformly so, and as the re- 

 quired force is far greater than a man's hand can well 

 produce, it becomes necessary to use a pile engine. In 

 this way the utmost certainty and uniformity are ob- 

 tained ; the former circumstance being extremely ne- 

 cessary, because, if imperfectly driven, these rockets 

 might burst on firing, to the great danger of the men 

 employed in that service. No description is required 

 of the pile engine, except to say that' it is provided 

 with a tell-tale for the purpose of regulating the num- 

 ber of blows given to each charge, as the force of the 

 blow is determined by the altitude or the weight of 

 the monkey. 



The first operation in filling the rocket is to put it 



* 3 



into the mould on the nipple, but without the spindle, Pyrotech. 

 and then to drive down on the choak a layer of fine ^ " y '_ [ _. 

 clay, about half an inch thick. This is carefully rammed, 

 first by light and then by harder blows, the workmen 

 turning the rammer round frequently, till it is beaten 

 as hard as a stone. The use of this coat is to serve as 

 a guard to the vent, to prevent the metal from being 

 destroyed by the burning torrent of fire. When this 

 is done, the rocket is to be removed from the mould, 

 and a hole must be bored through the coating of clay, 

 exactly equal to the vent hole. This hole ought to be 

 funnel-shaped, or widening inwards through the clay, 

 that the vent may run no risk of being choked during 

 the burning of the rocket. 



Being once more returned into the mould, and every 

 thing well secured, the rocket is ready for filling. The, 

 measured charge of composition being put in, it is to be 

 settled by hand on the bottom; and this is done by repeat- 

 ed strokes, till it is so firm that the condensation of air 

 which takes place in driving may not blow it out. The 

 driving of these large rockets is a very tedious process, 

 and requires the greatest precautions. As soon as the 

 composition is settled a little, in the manner just de- 

 scribed, four or five blows with the monkey must be 

 given from a height of five or six inches, taking care 

 that the composition does not push up between the 

 case and the rammer. It is then ready for the full 

 force of the engine ; and the monkey being raised to 

 six feet, the composition is to receive sixty strokes. At 

 each time the rammer must be lifted about an inch, 

 then turned about and placed close down on the com- 

 position again, otherwise the sudden condensation of 

 air by the blow might cause the rocket to take fire in 

 the mould. As the work proceeds, the rammers are to 

 be changed for those in succession that have shorter 

 bores ; but it is also necessary to examine them fre- 

 quently, to see that they are not choked with composi- 

 tion. Whenever this happens they are to be drilled 

 out clean ; but this must not be done in the rocket- 

 house, nor in any place where there is gunpowder or 

 composition present, as it is an unsafe operation. 



It is necessary to examine the rammers frequently 

 by means of a ruler, to see that they are not warped ; 

 and, in the whole of this work, much depends on the 

 care and prudence of the artificer who attends the 

 mould. When the charge has risen as high as the end 

 of the spindle, a solid rammer is to be substituted, and 

 the charge is to be completed. This part of the charge 

 should not exceed in length the diameter of the rocket. 

 If longer, it does not increase the flight or length of 

 range, and is very apt to render the instrument top-hea- 

 vy and unsteerable. 



The last operation in driving, is to ram the wadding 

 at the end of the composition, the chief use of which 

 is to prevent it from blowing out at the head before it 

 is burnt out. There are two methods of doing this. 

 The first is to lay a coating of clay about three quar- 

 ters of an inch thick on the top of it, and this is to be 

 rammed well down as it was on the vent. A plate of 

 iron with a hole in the centre is then to be placed on it, 

 which is to be fixed in its place by two pins laid on 

 it, and rivetted through on the outside of the case. 

 This being done, a hole is drilled through the clay 

 down to the composition, which must be carefully as- 

 certained to be the case, by taking a little of it out ; 

 and this hole must then be rammed full of mealed pow- 

 der, or of the fuse composition. The other method is 

 to place a block of beech wood upon the clay, which 

 is then perforated in the same manner ; and, to secure 



