Having filled some cases within about one diameter and a half, drive in a ladle full of clay, then pinch their ends close, and drive them down with a mallet; when done, find the center of gravity of each case, where you nail and tie a stick which should be half an inch broad at the middle, and run a little narrower to the ends these sticks must have their ends turned upwards, so that the cases may turn horizontally on their centers: at the opposite sides of the cases at each end, bore a hole close to the clay with a gimblet, the size of the neck of a common case of the same nature; from these holes draw a line round the case, and at the under part of the case bore a hole, with the same gimblet, within half a diameter of each line towards the center; then from one hole to the other draw a right line. This line divide into three equal parts, and at X and Y, Fig. 29, Plate III. bore a hole, then from these holes to the other two, lead a quick-match, over which paste a thin paper. Fig. 30, represents a tourbillon as it should lay to be fired, with a leader from one side hole A, to the other B. When you fire tourbillons, lay them on a smooth table, with their sticks downwards, and burn the leader thro’ the middle with a port fire. They should spin three or sour seconds on the table before they rise, which is about the time the composition will be burning, from the side holes to those at bottom. To tourbillons may be fixed reports, in this manner; in the center of the case at top, make a small hole, and in the middle of the report make another; then place them together, and tie on the report, and with a single paper secure it from sire, this being done your tourbillon is compleated. By this method you may fix on tourbillons, small cones of stars, rains, &c. but be careful not to load them too much. One eighth of an inch will be enough for the thickness of the sticks, and their length equal to that of the cases. The Manner of making Mortars, for throwing Aigrettes and loading and firing the same.