PYIIOTECHNY. 



I'yrotcch- 

 ny. 



high angle for a long range, and are also employed in 

 this way to carry a shell ; thus producing the 

 of hou They have, however, Urn found prin- 



cipally of use in the latter case; and for this pu 

 the siae is of less moment, provided the range is Mifli- 

 ciently gM'at. To produce the best eH'.-r!- in this 

 way, they are placed on the ground, and fired at very 

 low angles, which may be varied according to the in- 

 tended raii-'e. In this manner, after they first strike 

 the ground, they rebound again, like a ricochet shot ; 

 and as this may happen many times in the case of 

 the rocket, just as it does in that of the shot, the 

 alarm thus excited among horses is so great, as to 

 break or disturb the order of the squadrons. This 

 effect is -further increased by the uncertain directions 

 which they take niter each rebound, from the manner 

 in which they strike; so that it serves no purpose for 

 the lines to open a way for them, as they may fly 

 sidewise, or even return backwards among the 

 horses. 



As we must not here enter further on these ques- 

 fishing. tions of military operations, we shall now add that the 

 same rockets have lately been used in the whale fish- 

 ery, instead of the harpoon. When fired successfully, 

 they not only penetrate deeply into the fish, but by 

 burning and exploding within him, he is immediately 

 killed, so as after a short plunge, or sometimes without 

 any, to float on the surface of the water. Thus all the 

 labour, expence, and risk of running out lines is 

 avoided, while the prey is secured without the possi- 

 bility of escape. 



As the sizes and weights of iron rockets are often 

 considerable, the latter reaching from sixteen even to 

 forty-two pounds, a particular apparatus, or frame, 

 is required for firing them. It is also necessary that 

 proper carts should be provided for carrying them in 

 the field ; and as it further requires practice and ex- 

 perience in the men to make use of them effectually, 

 and to avoid hazard, a regular rocket establishment, 

 both of men and carriages, has been introduced into 

 our military service by Sir William Congreve, to whom 

 we are indebted, not only for the original proposition, 

 but for every thing that has been done in this depart- 

 ment, whether with regard to the mechanical and py- 

 rotechnic part, or the military arrangements. As it is 

 not here our business to enter into these, we shall pro- 

 ceed to describe the construction of the rockets them- 

 selves, from the French publications, in as far as that 

 is already before the public. In our own country, 

 these are circumstances which it has, for very good 

 reasons, been thought proper to reserve from the gene- 

 ral curiosity. 



Construction of Iron Rockets. 



Construe- The principle of the iron rocket is the same as that 

 tion of iron of an ordinary signal or ornamental one. But, on ac- 

 rockets. count of the greater diameter, it is necessary to use 

 cases made of iron instead of paper. Many advantages 

 flow from this change. By diminishing the diameter, 

 the resistance of the air is also diminished, and thus the 

 length of the range, which is a very important cir- 

 cumstance in war, is also increased. The bulk, and 

 consequent stowage, is thus also diminished, which is 

 in itself a valuable consideration. In a similar man- 

 ner, the strength of the cases is greater, so that they 

 are better able to bear the driving. But the principal 

 advantage is that without which they would, in many 

 cases, not answer their purposes at all, namely weight 



sufficient to allow them to penetrate; whether into Pyraucb. 

 houses or magazines, or into the bodies of men or ani- 

 malt. The sharp conical iron head is, in fact, en 

 tienthl p.-irt of the weapon ; and thin could not be used 

 at all, unless the whole case was made of the same ma- 

 trri.il. On comparison, the difference of expence be- 

 tween cases of paper and of iron will not be found to 

 great as it appears at first sight. 



The case is a cylinder of sheet iron, as soft in quali- 

 ty as can be procured. It i* dovetailed in the longi- 

 tudinal joint, where it is also brazed; and, for a diame- 

 ter of three inches, the iron need not be more than 

 one-fifteenth of an inch in thickness, increasing or di- 

 minishing as may be necessary, for the larger and 

 smaller sizes. The inside of this case is lined with 

 a single fold of cartridge paper pasted on. At the 

 vent end, a cup is brazed on, which may be made 

 either of iron or copper, and through this the vent or 

 choke-hole, properly calculated for the diameter of the 

 case, is made. The cap is an iron cone, also of plate 

 iron, which is fixed on after the rocket is driven, and 

 which either carries a charge of powder, or a burning 

 composition like that used for carcases ; in this case 

 the cap is perforated with two or three holes, and is 

 then surrounded by painted canvass. 



In making these cases, a very different apparatus is 

 required from that used for paper-rockets. A block, 

 or more, of tough oak or elm, must be provided, in 

 which semicylinders are cut, of such sizes as to take 

 in each diameter of rocket that is to be made. An 

 iron solid cylinder, or rather a number of these, of 

 diameters adapted to each scale of rocket, is the next 

 tool required for making up the cases. Besides these 

 there are required all the tools of a brazier and worker 

 in sheet-iron, such as scissars, hammers, anvils, files, 

 vices, drills, &c. 



The requisite dimensions of the rectangle which 

 will cover the iron cylinder being measured, with an 

 additional allowance on the largest side for dovetail- 

 ing, it is to be folded over the mandril or centre, so as 

 to overlap at the joint, and then wrought with the 

 hammers on the grooved block till it fits as close as 

 possible in every part except the intended joint. 

 Having done this, the dovetails are then to be cut out 

 by means of the cold chisel and file, and then the 

 whole is to be put together, and closely fitted all round 

 the mandril. When this is done, it is to be well 

 wrought with the hammer, till the mandril will slip 

 in and out with equal ease in all parts. Four rings, 

 or hoops of iron, must then be driven on the case, thus 

 far finished, to prevent it from starting, besides which 

 an iron wire may be wound round it Jt is then 

 ready for brazing, and must be carefully brazed along 

 the whole joint in the usual way. 



After' this it must again be put upon the mandril, 

 and dressed in the block till the former slips easily 

 in and out, and till the surface is uniformly smooth 

 and even. If any holes or defects are now discovered 

 in the brazing, they must be repaired. The cup for 

 the vent-hole, which has previously been hollowed to 

 the proper shape for fitting upon the nipple of the 

 mould, must now be bored to the proper dimensions ; 

 taking care that it lies equally round the axis of the 

 rocket. For this purpose it must be perfectly centred 

 in a lathe. 



The case must next be lined with cartridge paper. 

 For this purpose the mandril is first soaped, and the 

 paper is rolled and pasted over very slightly, so as just 

 to hold upon it. The outside is then covered with 



