The second mutation is thus made. Have a nave, turned two and a half inches in diameter, and three long; then let half an inch of that end, which faces the first wheel, be turned, so as to fit easy into the tin barrel of the first mutation, which must turn round it without touching. On the other end of the block, fix a tin barrel No. 2. This barrel must be six inches long, and only half an inch of it to fit on the block. Round the nave, fix five spokes, one inch and a half long each. The diameter of the spokes must be equal to a two-ounce former. On these spokes, put five seven-inch two-ounce cases of spur-fire, and carry leaders from the mouth of one to the other, that they may all light together. Then, from the mouth of one of these cases, carry a leader through a hole bored slantwise in the nave, from between the spokes to the front of the block, near the spindle hole. The end of this leader must project out of the hole into the barrel of the first mutation; so that, when the pipe, which comes from the end of the last case on the first wheel, flashes, it may take fire and light the second mutation. To communicate the fire to the third mutation, bore a hole near the bottom of one of the five cases to the composition; and from thence carry a leader into a hole, made in the middle of the barrel. This hole must be covered with pasted paper.
The third mutation may be either an octagon or hexagon wheel, twenty inches in diameter. Let the nave be three and a quarter inches in diameter, and three and a half in length. One and a half inches of the front of the nave must be made to fit in the barrel No. 2. On the other end of the block, fix a tin barrel No. 3. This barrel must be six and a half inches in length, one inch of which must fit over the block. The cases of this wheel must burn two at a time, and, from the mouths of the two first cases, carry a leader through holes in the nave, into the barrel of the second mutation, after the usual manner. But besides these leaders, let a pipe go across the wheel from one of the first cases to the other. Then, from the tail of one of the last cases, carry a pipe into a hole in the middle of the barrel No. 3: at the end of this pipe, let there be some loose quick match.
Fourth and Fifth Mutations.—Their naves are made of one piece, which, from the barrel of the fourth, to the commencement of the sixth, is fourteen inches. The block of the fourth is four inches in diameter, having ten or twelve short spokes, on which are fixed eleven inch eight-ounce cases. The front of this block must fit easy in the barrel of the third wheel. Clothe the cases, so that they may all light together; and let a pipe be carried through a hole in the block into the barrel No. 3, in order to receive the fire from the leader, brought from the last case on the wheel. The nave of the fifth mutation must be four and a half inches in diameter, and furnished with ten or twelve spokes, eighteen inches in length each. These spokes must stand seven inches distant from the spokes of the fourth mutation, and, at the end of each spoke, tie a four-ounce case as No. 5. All these cases are to be lighted together, by a leader brought from the end of one of the cases on No. 4.
Sixth and Seventh Mutations.—The blocks of these two mutations are turned out of one piece of wood, whose length from the barrel of the fifth wheel, to the block of the eighth wheel, is fifteen inches. The block of the sixth wheel is five inches in diameter, having eight spokes, each two feet four inches long. At the end of each spoke, tie two four-ounce cases, as in No. 6. All these cases must be fired at the same time, by a pipe brought from the end of one of the cases on the fifth mutation. Let the distance between the spokes of the sixth, and those in the fifth mutation, be seven inches. The nave of the seventh mutation must be five and a half inches in diameter, and furnished with eight spokes. On the front of them, two circular fells, one of four feet eight inches in diameter, and the other, three feet eleven inches, are to be fixed. On these fells, tie sixteen eight-ounce cases, or pound cases, as in No. 7, and carry leaders from one to the other, so that they may be fired at the same time. This mutation must be fired by a leader, brought from the tail of one of the cases on the sixth mutation.
Eighth and Ninth Mutations.—The blocks of these may be turned out of one piece, whose length from the barrel of the seventh mutation to the block of the ninth, must be twelve inches. The block of the eighth, six inches in diameter, must contain six spokes, each three feet in length, and strengthened by an hexagon fell, within three or four inches of the ends of the spokes. Close to the end of each spoke, in the front, fix a five-pointed brilliant star, and seven inches below each star, attach two ten-inch eight-ounce cases, so that the upper ends of the cases may rest on the fells, and their ends on the spokes. Each of these cases must be placed parallel to the opposite fell.
Ninth Mutation.—The block of the ninth mutation is seven inches in diameter, and holds six spokes, six feet long each, with holes and grooves for leaders, as those in the dodecaedron. At the end of each spoke in the front, fix a spindle for a hexagon vertical wheel, ten inches in diameter, as in No. 9. When these wheels are on, carry a leader from each into the block, so that they may all meet. Then lead a pipe from the end of one of the cases of the eighth mutation, through a hole bored in the block of the ninth, to meet the leaders from the vertical wheels, in order that they may be fired together.
Having thus given a brief description of this complicated work, the performance of which depends so much on the accuracy of its parts, we will now add a few remarks respecting the formation of spindles.
For the larger pieces, the spindles should be made very strong and exact. The instructions on this head are, that for a piece of nine mutations, let the spindle be, at the large end, one inch in diameter, and continue that thickness as far as the seventh mutation, and from thence to the fifth, let its diameter be three-quarters of an inch. The other proportions, then, are, from the fourth to the second, half an inch; and from the second to the end, three-eighths of an inch. At the small end must be a nut, to keep on the first wheel, and at the thick end, a large nut; so that the screw part of the spindle being put through a post, and a nut screwed on tight, the spindle will be held fast and steady. The wheels, however, ought to run easy and without sticking. The fixed pieces are made on different blocks, and the leaders must be joined, after they are fixed on the spindle. The best method of preventing the fixed mutations from moving on the spindle, is to bore a hole a little larger than the diameter of the spindle; and, at each end of the block, over the hole, fasten a piece of brass, with a square hole in it to fit the spindle.
Similar to this piece of nine mutations is the Pièce Pyrique of the French, which consists of a great variety of fixed and moving pieces, that are fired alternately, but in regular succession. This piece we purpose to describe in the following section.
Sec. XIX. Of the Pyric or Fire-Piece.