The ninth mutation must be thus made; let D be a block seven inches diameter; in this block must be screwed six spokes, six feet in length each, with holes and grooves in them for leaders, in the same manner as those in the dodecaedron; at the end of each spoke, in the front, fix a spindle for a hexagon vertical wheel, ten inches diameter, as shewn by Nᵒ. 9. When these wheels are on, carry a leader from each into the block, so that they may all meet together; then lead a pipe from the end of one of the cases of the eighth mutation, through a hole bored in the block D, to meet the leaders from the vertical wheels, so that they may all be fired together. The spindles for large pieces are required to be made very strong, and as exact as possible; for a piece of nine mutations, let the spindle be at the large end one inch 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; from the fifth to the fourth, five eighths of an inch; 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 must be a large nut, as shewn by the figure, 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; but you are to observe, that that part of the spindle, on which the moveable pieces are to run, be made long enough for the wheels to run easy without sticking; the fixed pieces being made on different blocks, 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 make that part of the spindle which goes through them square; but as it would be difficult to make square holes through such long blocks as are sometimes required, it will be best to make them in the following manner; which is, to bore a round 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. To make a Horizontal Wheel change to a Vertical Wheel with a Sun in Front.