Fuzes for air ballóóns are sometimes turned out of dry beech, with a cup at top, to hold the quick-match, as you see in Plate II. Fig. 28, but if made with pasted paper, they will do as well: the diameter of the former for fuzes for coehorn ballóóns, must be half an inch; for a royal fuze, five eighths of an inch; for an eight inch fuze, three quarters of an inch; and for a ten inch fuze, seven eighths of an inch. Having rolled your cases, pinch and tie them almost close at one end; then drive them down, and let them dry; before you begin to fill them, mark, on the out side of the case, the length of charge required, allowing for the thickness of the bottom; and when you have rammed in the composition, take two pieces of quick-match, about six inches long, and lay one end of each on the charge, and then a little meal powder, which ram down hard; the loose ends of the match double up into the top of the fuze, and cover it with a paper cap to keep it dry. When you put the shells in the mortars, uncap the fuzes, and pull out the loose ends of the match, and let them hang on the sides of the ballóóns; the use of the match is, to receive the fire from the powder in the chamber of the mortar, in order to light the fuze: the shell being put in the mortar with the fuze uppermost, and exactly in the center; sprinkle over it a little meal-powder, and it will be ready to be fired. Fuzes made of wood must be longer than those of paper, and not bored quite through, but left solid about half an inch at bottom; and when you use them, saw them off to a proper length, measuring the charge from the cup at top. Of Tourbillons.