For this piece, a circular table is formed about twenty inches in diameter, and one inch and a quarter thick. There is a hole made in the centre, which is furnished with a pivot.
Twelve inches from the circumference, and at equal distances, eight holes are to be bored, to receive the same number of pots, of two inches caliber; and, in the immediate vicinity of the centre hole, which receives the pivot, four more are made, for four other pots.
Eight arms, three inches long, project from the table at equal distances, on which is fastened a hoop one inch in width. The fire-pots are now put in the different apertures, which are made sometimes to screw in; and the frame, of which we have spoken, is furnished with cases of brilliant fire.
It is necessary that this piece should go off at three fires; but the order of firing may be varied according to circumstances.
Sec. XVIII. Of the Projected Regulated Piece of Nine Mutations.
A regulated piece, if well executed, is considered as curious in its effect as any other in pyrotechny. It consists of fixed and moveable pieces on one spindle, representing various figures, which take fire successively one upon another, without any assistance after lighting the first mutation.
I. Names of the mutations, with the colour of fire, and size of the case, belonging to each.
First Mutation.—This is a hexagon vertical wheel, illuminated in front with small port-fires, tied on the spokes. This wheel must be clothed with two-ounce cases, filled with black charge. The length of these cases is determined by the size of the wheel, but each must burn singly.
Second Mutation.—This is a fixed piece, called a golden glory, by reason of the cases being filled with spur fire. The cases must stand perpendicular to the block, on which they are fixed, so that, when burning, they may represent a glory of fire. This mutation is generally composed of five, or seven two-ounce cases.