Pin wheels.
3. Pin wheels.—Pin or Catherine Wheels are of very simple construction, nothing more being wanted than a long wire former, about three sixteenths of an inch diameter; on this wire are formed the pipes, which being filled with composition are afterwards rolled round a small circle of wood, so as to form an helix or spiral line.
The cases are generally made of Elephant paper, or such as will admit of the greatest length; rolled about four times round the wire and pasted as they are rolled; when a number of pipes are made and got perfectly dry, they are filled with the composition described at No. 2, in the table; these cases are not rammed, but filled by means of a tin funnel with a long pipe, made so as easily to pass down the case, which is gradually filled by shaking the composition out of the funnel; all the cases prepared being thus filled, one of them being closed at one end, is to be pasted round the flat circle of wood, which must not be above half an inch thick, and one inch in diameter, and secured at every half turn by sealing wax; when this is all wound round the circle and the wheel not sufficiently large, a second case may be inserted into the mouth of the last, taking care that the end introduced is only loosely twisted, otherwise it might obstruct the communication and destroy the effect; but this being properly adjusted and the joining secured by pasting paper round it, the spiral is to be continued in the same way as before, till the wheel be increased to the proper dimensions, or such as suits the taste of the Tyro.
The central block must be pierced in the middle for the purpose of receiving a strong pin, or a small piece of wire, by which the wheel may be attached to a post or any other convenient object, or the pin or wire being inserted into the pith of an hazel stick, the wheel without any danger may be let off in the hand; when the mouth of the last round is primed and capped with touch-paper, on its being lighted, the impulse of the flame against the air forces back the ignited part of the wheel, which continues to revolve till the whole of the composition is consumed.[7]