236 



PYROTECHNY. 



l'> rotech- trial of the equipoise, the tail is too heavy, it may be 

 n y* lightened by the plane ; if too light, that part of the 

 """ Y """ * stick which is fastened to the rocket may be slipped 

 down a little lower. 



Table of Rockets. For one complete. 



The same proportions are applicable to all other dia- 

 meters, except as to the length of stick ; for which the 

 following table may be consulted. 



Dimensions and Poise of Rocket Sticks. 



We may add to these numbers, that a general length 

 may be considered, as 60 diameters for the smaller 

 rockets, and 50 for the larger ; that half a diameter is 

 a good general rule for the top of the stick, and a 

 quarter for the extremity ; but that provided the equi- 

 librium be correct, they cannot exceed in length, how- 

 ever long ; although they will not admit of being 

 shortened, as the steerage depends on the distance of 

 the extremity from the centre of gravity of the whole. 

 There are many projects for varying the effects of 

 rockets, which are described in the books of pyrotech- 

 ny, and we shall enumerate them for the satisfaction of 

 our readers. We shall, however, take the liberty of 

 noticing their nature as we go along, as it will be found 

 that some of them are difficult of execution, and others 

 impracticable; or rather that they do not produce the 

 anticipated effects. It is useful to know what to avoid, 

 to save both expence and disappointment ; and it will 

 be found that, in practice, modern pyrotechnists have 

 abandoned most of these schemes, although they still 

 stand recorded in their works. 



PLATE The Caduceus rocket, as it is called, consists of 



CCCCLXXH. two rockets fixed to one stick. For this purpose 

 Fig- 6. the rockets must have no heads, as they are unable, 

 from the great resistance which they offer to the 

 air, to carry any unnecessary weight. To enable 

 them to ascend, it is prudent not to place them at a 

 greater angle to each other than 40 or 45 degrees ; and, 

 indeed, the less the angle is, so much the more certain 

 and steady will their flight be. At the upper extremi- 

 ty, they must be fastened, the one before, and the other 

 behind the stick. At the lower, they are to be attach. 

 ed to a transverse bar, which is also fastened upon the 

 stick, so as to form an equilateral triangle. But it is 

 to be observed that they must not lie in one plane ; 



Caduceus 

 rocket. 



and this object is effected by passing the lower extre- Pyrotech - 

 mities on the alternate sides of the transverse bar, in 

 directions the reverse of that which they have at the 

 upper extremity. Thus, the tendency of each rocket 

 becomes such as to compel them to turn ri a spiral 

 round the line of flight, forming that particular appear- 

 ance whence the name is derived. The stick is re- 

 quired to be considerably longer than for simple 

 rockets, and the centre of equilibrium of the whole 

 should be at least one length of a rocket from the vents. 

 In firing them, it is necessary to be careful that they 

 light together, and great care is required in the sus- 

 pension. With all these precautions, the performance 

 of this compound rocket is awkward and uncertain. 



It has been attempted to fire one rocket from the 

 head of another after that is expended, and this inven- 

 tion is called a towering rocket. To put this scheme 

 into effect, a pound rocket will be required to carry a 

 four ounce, in the following manner. The upper end 

 of the large rocket is left unfinished, with a sufficient 

 projection of the case beyond the charge to receive the 

 mouth of the small one. This latter is then fixed loose- 

 ly into it by means of a little tow, with some paper, 

 lightly pasted round; so that when the principal rocket 

 is expended, the secondary one may have no difficulty 

 in disengaging itself. The stick of the small rocket is 

 brought down parallel to that of the large one, and slight- 

 ly secured in a similar manner. Thus, when the prac- 

 tice happens to succeed, the small rocket will take fire 

 and continue its ascent when the principal one is done. 

 We must, however, remark, that this is somewhat of a 

 theoretical rocket ; a thing not unusual with pyrotech- 

 nists. The check which this additional weight gives 

 to the principal one is very apt to derange its flight ; 

 while the slightest irregularity in the disengagement of 

 the secondary one will ruin the expected effect, and 

 cause it to overturn and fall down with the burnt 

 stick and case of the first. The effect gained by it is 

 at the same time so trivial, even when it does by chance 

 succeed, that it is not worth the trial and risk of failure. 

 Should any one think fit to try this experiment, it must 

 be recollected that a stick considerably longer than for 

 a simple rocket will be required. 



There is a project called an honorary rocket, PLATE 

 equally hazardous in the performance, but which CCCCLXXH. 

 we must also describe. In this construction, the case *"' 7 - 

 or rocket has no head, for the same reasons. Sup- Honorary 

 posing it be a two pound rocket, as a smaller one will rocket, 

 scarcely answer the purpose, a notch must be made 

 in the case, just where the charge and the clay termi- 

 nate, fitted to receive a transverse case or subsidiary 

 firework. For the size now mentioned, it may be what 

 is called a four ounce case, not exceeding six inches in 

 length. This is driven solid with the same composi- 

 tion as the rocket itself, or with that used for tourbillons, 

 since it is in fact a tourbillon, and is closed at both 

 ends. It is then bored with two deep gimlet holes 

 close to the extremities, on opposite sides, and so that 

 the direction of these is at right angles to the rocket, or 

 horizontal. The case thus finished is fixed to the top 

 of the rocket, and a leader of quick-match is brought 

 from each of its openings to the hole which communi- 

 cates with the end of the composition, after which the 

 rocket head is covered, as usual, with a paper cone. 



The effect of this is easily understood. When the 

 rocket is expended and the stick has turned to de- 

 scend, the transverse case takes fire at both ends and 

 spins round the line of descent, so as to form, if sue- 



