P Y R T E C H N V. 



245 



Of tour, 

 billon*. 



PLATE 

 CCCCLXXII 

 Fig. 8. 



1'jrrotech- the circle is enlarged, the velocity of direct motion \\ .11 

 n y- be diminished, and the reverse. 



T"' '1 Ins variety of the line rocket may also be doubled. 

 To eflect this, four cases will be required, two for the 

 retreat and two for the advance or return ; and they 

 must, of ewurse, be placed parallel, so that the tame 

 direction of the revolution may be maintained in one 

 way as in the other. It is easy to understand how the 

 leaders are to be managed in this case; while it must 

 be recollected that to preserve the balance, the opposed 

 cases must burn together. 



Qf Tourbillons. 



This is infinitely the most brilliant and surprising 

 of all the simple fireworks ; but, unfortunately its career 

 is as short as it is splendid, as there is scarcely time to 

 see it before it is burnt out. These fireworks should, 

 ' therefore, be numerous in all public displays ; though, 

 from the difficulty of making them, artists are very apt 

 to be economical in their use. Yet as these are cheap 

 in proportion to their brilliancy, and cannot fail to 

 succeed in good hands, they ought never to be omitted. 

 We have given a drawing of the construction of this 

 firework, as it is difficult to make it by a verbal direc- 

 tion only. The principle is simple, and by explaining 

 that first, the reader will the better understand the 

 following directions. Its effect is that of a wheel which 

 revolves and ascends at the same time ; and as this is 

 done by a single case, in a most ingenious manner, it 

 is evident that it requires two distinct kinds of re- 

 coil. 



The one pound case is the largest that should be 

 used for the tourbillon, and it is of very little use to 

 make them less than the half of that size, or eight 

 ounces. The length may vary from eight to nine di- 

 ameters. Before driving, the case should be choked 

 close at the lower end, and it must be driven as hard 

 and as carefully as a sky rocket. Ordinary rocket 

 composition may be used for it, or, what is better, a 

 strong brilliant fire with iron, a receipt for which will 

 be found in the table of compositions. When the case 

 is nearly filled, the upper end of it must be turned in 

 with a little glue, fold after fold in succession, and well 

 beat down with the rammer, so that both ends may be 

 alike secured. 



The case thus ready, must be bored either with a 

 greased gimlet or with the drill, as formerly describ- 

 ed. As every thing in the performance depends on 

 the boring, this requires great attention. A hole is first 

 to be made close to each end of the case, but on oppo- 

 site sides, and equal in diameter to half the diameter 

 of the charge, or exactly equivalent to the bore of a 

 sky rocket. By means of these holes the revolution 

 of this firework is effected, so that it is so far a single 

 case wheel. On that side of the case, which is a qua- 

 drant removed from these two holes, or which would 

 be the bottom side if it were it laid on a table with a 

 hole looking sidewise each way, a line must then be 

 made, and divided into three equal parts between the 

 space which is included between the two holes just de- 

 scribed. A hole must now be bored in each of the two 

 middle points just described, at right angles to the axis 

 of the rocket, and to the direction of the side holes 

 also. Thus the composition is divided by means of 

 these two holes, and the first two at the ends, into three 

 equal parts. The last holes must be of the same di- 

 ameter as the first, or equal to one-half the diameter of 

 the composition. 

 It may now be understood, that if this firework were 



laid with these two intermediate hole* directed down* 

 wards, the fire issuing from them would give it a ten- 

 dency to ascend, by means of this vertical recoil. But 

 although this is the case to a certain degree, there is 

 yet not power enough for that purpose. To obtain this, 

 a hole must now be bored, as nearly as possible in the 

 direction of the axis of the rocket, from each of the 

 t\\<> middle ones towards the end, and until they have 

 readied to within a diameter of the composition of each 

 end hole. Thus the tourbillon becomes a kind of 

 double sky rocket, as far as the two lower holes are con- 

 cerned, while it continues to be a wheel by means of 

 the end ones. It is evident, therefore, that it will now 

 ascend by the recoil from the lower holes, while it will 

 revolve on ite centre by that from the end ones, and 

 the velocity will increase as all these holes come, in the 

 progress of burning, to communicate together. 



To complete this rocket for firing, all the holes must 

 be caused to communicate by a single leader. A stick 

 is then to be fastened on it transversely. This is made 

 of a thin and light broad piece of deal, and the fastening 

 is made so that it lies between the two bottom holes, and 

 in such a manner as to form a point on which it may 

 revolve freely when placed on a table. Care must, at 

 the same time, be taken that it is perfectly and nicely 

 balanced on this point, without which its performance 

 will not only be incorrect, but very dangerous to the 

 bystanders, should it, in flying off the table, take a ho- 

 rizontal course. The stick should not, therefore, be 

 finally fastened until the operator is sure of a perfect 

 equilibrium. In firing, it is placed on a table with the 

 two lower holes downwards ; and, after spinning for a 

 second, it ascends with a rapid and noisy circular mo- 

 tion. The books of pyrotechny order various orna- 

 ments to be appended to it, such as stars and crackers ; 

 but this is impossible, as its nature is so delicate that 

 it will not bear the slightest weight or incumbrance 

 of any kind ; besides which, its duration is far too short 

 for such contrivances, as it does not burn above four 

 or five seconds. We may add, that there is no better 

 test of an artist's accuracy than a good tourbillon, and 

 that a slovenly one need not attempt it. 



Of Table Rockets. 



This kind of firework is not applicable to public Of uble 

 exhibitions, because it is not sufficiently visible at a 

 distance. But it is well adapted for a small number 

 of spectators, and is very ornamental, while it is at 

 the same time a test of the artist's accuracy of work- 

 manship. The case is filled and managed in every re- 

 spect like the tourbillon, but the composition may be 

 varied in different parts, so as to produce some changes 

 of appearance during the burning. But it must be 

 remembered, that whatever composition is introduced 

 at the first end in driving, the same must be done for 

 the others, that both the ends may regularly corre- 

 spond in quality all the way to the centre. Supposing 

 it therefore to be eight diameters in length, which is 

 sufficient, the first diameter, or inch, if it is an inch 

 case, may be filled with a strong charcoal fire, for 

 which receipts will be found in the table. This may 

 be followed by the same quantity of brilliant iron fire. 

 Both of these may be strong compositions, that the 

 firework may acquire sufficient velocity at the com- 

 mencement. Half an inch, or less, of a rlaming and 

 slow fire, without sparks, may then be introduced, 

 which is again to be succeeded by a strong one, to 

 give it an opportunity of recovering its velocity, and 



