PYROTECH.NY. 



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Tyroicch- every thing but the central holos, and in exactly the 

 ecroll formerly described, with the addition of an 

 and centre. They may, however, be made of 

 double the length of cases for all other purposes, or of 

 ny length from eighteen to twenty-four interior dia- 

 meters. Thus t>ie half inch wheel will be a foot long, 

 If more, they will still act well, provided that both ori- 

 fices are fired together. 



In driving them, a mould must be used; as the same 

 hardness and regularity of composition are required as 

 in the tourbillon. The compositions may also be varied, 

 as was described just now for hexagonal wheels ; but 

 in doing this, if the wheel is a simple case, perforated 

 at both ends, the artist must recollect that whatever 

 composition is placed at one end, the same ought to 

 be placed at the other ; but in a reverse order, so that 

 the circle of fire may be uniform. Yet a variety is also 

 admissible, by entirely reversing the quality of the 

 composition at opposite ends ; so that while one orifice 

 is producing a sparkling fire, the other may give a 

 blue or a white flame. We need scarcely add, that the 

 compositions may be selected from the table at the 

 artist's pleasure; but as this wheel is eo short and 

 light, that little force is required to put it in motion, the 

 operator need not be anxious about using strong fires. 



In driving this case, one end must first be choked 

 quite close ; or, what is better, the ends of the folds 

 should be turned in with glue, and beat down square 

 and solid, so that there may be as little unnecessary 

 length as possible. The centre of the case must then 

 be measured and marked upon the case and rammer 

 both, and half a diameter must then belaid down upon 

 the latter, on each side of this line. Thus, when the 

 artist has arrived at this point, he will have notice, 

 without farther trial, that the first half of the case is 

 filled. Clay is then to be introduced and beat down 

 with the same degree of force, so as to form one dia- 

 meter. In the larger cases, indeed, less will answer 

 the purpose, as the only object of this is to form the 

 centre through which the axis is to be inserted. This 

 at least is the common practice ; but we have found 

 that these wheels answer their purpose equally well 

 without any central clay, while, at the same time, they 

 burn a little longer when made in this manner. Which- 

 ever plan is adopted, the case is to be completed to 

 the upper extremity, when the ends of the folds are 

 to be turned down with some paste or glue, and driven 

 down solid by means of the rammer. 



The case is then ready for boring. To do this accu- 

 rately, four lines must be drawn upon it, parallel to 

 the axis, at equal distances, so as to divide the circle 

 into four quadrants. By means of a bit of string to 

 suspend it, the centre of equilibrium must then be 

 found, and a mark made for the hole which is to be 

 bored through it for the purpose of carrying the spin- 

 tile. This hole need not exceed a quarter of the inte- 

 rior diameter ; and being done, the edges of the paper 

 are to be rubbed down smooth with grease, and a bit 

 of tallow introduced into the hole, to remain there till 

 the firework is wanted for use. The spindle must be 

 well fitted to this hole, yet not too tightly, and polished ; 

 and it must also be provided with a nail head so smooth- 

 ly turned inside, as not to check the motion of the 

 wheel should it come into contact with it during its 

 revolutions. When it is to be put on the spindle, a 

 small hemispherical button of wood should also be 

 forced on afterwards, to retain the wheel in its place, 

 and prevent it from coming in contact with the sup- 

 port, of whatever nature, to which the spindle is to be 



These precautions are necessary, at least fat l : yrot c h 

 the larger wheel* of this clas ; llthough, in the *-. 

 they maybe dispensed with | and, we need s< - 



ndd, that all these rubbing parts should be well 

 greased. 



It is next necessary to bore the case for firing. 

 i^ done, as in the tourbillon, at th lies of 



case, and on opposite sides, and on those two lines 

 which are at right angles to the two through which 

 the axis passes. Thus, when the fire issues from 

 these, the case revolves like a wheel. These holes 

 must be equal in diameter to half a diameter of the 

 composition ; and the artist ought here to be reminded, 

 that a set of gimblets, accurately measured from the 

 eighth of an inch upwards, and numbered, muet form a 

 part of his establishment of tools. 



It only remains to prime the wheel, which is done 

 by carrying a single leader from one orifice to the other, 

 and securing it with pasted paper at each. To the 

 middle, an additional leader is attached in the same 

 manner, which i* reserved of an indefinite length, to be 

 afterwards adapted to any place that may be required. 



It is possible to prolong the action of these wheels 

 by burning only one hole at a time, and causing the 

 common leader to commence near the axis on one side, 

 and be inserted into the second orifice. In this case 

 the first priming leader is inserted into one orifice. 

 A wheel so constructed burns and revolves very regu- 

 larly at first, but is apt to become irregular as the equi- 

 librium is destroyed. To prevent this, the commu- 

 nicating leader may be inserted half way between the 

 axis and the first orifice ; and thus the burning of the 

 wheel is prolonged for one-half more the time that it 

 would be if lighted at both ends together. 



Such wheels may also be varied, so as to give two 

 circles of fire instead of one ; and this has a good ef- 

 fect, particularly if they are of large size. Even three 

 circles may be introduced ; but in this case it is neces- 

 sary that the firework should be of extraordinary length, 

 as it would otherwise burn out too quickly. In bor- 

 ing for the former purpose, one of the holes should be 

 made towards the axis, and the other at the extremity, 

 still however on opposite sides ; and if three circles 

 are wanted, it is easy to understand that two more op- 

 posed holes are to be made at a convenient intermedi- 

 ate distance. The arrangement of the leaders for this 

 purpose is easily comprehended ; and the operator may 

 also understand how the effect of such a wheel will be 

 improved, by forming the external circle of brilliant 

 fire, and the internal one of a white or blue light 



This kind of firework, from its great simplicity, ad- 

 mits of being easily compounded, so as to produce 

 very pleasing effects. To describe one mode, will sug- 

 gest to the artist many other ways of producing variety 

 from this expedient. Two or more cases differing in 

 length may be fixed on an axis ; each being secured 

 in its place by an intermediate button, so that they may 

 not interfere in their revolutions. If two, for example, 

 are used, the one should be made to revolve in a direc- 

 tion the reverse of the other, which is easily managed 

 by a proper position of the vent holes. Thus also 

 many concentric circles of fire can be produced, either 

 in the same or opposite directions, by placing many 

 cases of different lengths on the same axis. 



But in doing this, the larger cases should have quick- 

 er compositions than the inner ones, so that they may 

 not last much longer. Or, what is still better, each 

 wheel leader should be separate, and all of them pro- 

 vided with bits of slow-match of different lengths. 



