The port-fire is used as a means of lighting the pieces, etc., of a display, and in the last century for military purposes; its composition consists of a mixture of saltpetre, sulphur, and mealed gunpowder. It was formerly known as a blue candle. The starlight and feathers, as are the squib, golden rain, etc., are of the garden type, and are not used in display work, as although burning with pretty effect, it is not distinguishable at any distance. The feather and starlight compositions are similar to that of the flower pot, but the cases are smaller, that of the feather being catherine wheel pipe, but naturally not bent—the ends are closed by “dubbing.” This is a method usually adopted for closing the ends of “small goods.” The end of the case is introduced into an opening formed by opposing V-shaped notches in an upper and lower series of steel plates, the upper set being then forced down. The result is to constrict the end of the case, which is then dipped in a mixture of sealing-wax and glue. Under the same head fall the Light group, which are wide and comparatively thin cases filled with coloured or “bright” (as white composition is known in the trade) composition. They are used either for illuminating as Bengal lights, or for signalling purposes; if for the latter, they are generally provided with a wooden handle and some means of self-ignition. The name Bengal light is probably based on the use of Bengal saltpetre, and does not indicate their origin in that province. CHAPTER V COMPOUND FIREWORKS Compound fireworks are those which are composed of a number of simple fireworks or units fixed to a framework or other device so that they produce a more elaborate effect than do single fireworks. Probably the earliest form of compound firework was the wheel. After the sky rocket had become an established fact, it was a small step to tie rockets round a wheel, so that when fired they caused it to revolve. Babington gives several devices based on the idea of imparting movement to a wheel by rockets: he describes horizontal and vertical wheels, which appear to be the same piece fired either horizontally or vertically. In neither case is there any further effect than the fire from the rockets tied to the periphery. His illustration shows no less than sixteen rockets to fire singly in succession, which would, by modern standards, make a rather lengthy and monotonous piece. He also describes ground wheels, which consist of two wheels fitted to an axle with a smaller wheel placed centrally between them. The centre wheel has rocket cases fitted to it, causing the whole arrangement to revolve and run along the ground. As an alternative he suggests substituting cases secured to the axle without a central wheel, so arranged that one being burnt out the second burns in the opposite direction and reverses the direction of the wheels. The device is now quite obsolete.