The cases for rockets, as a general rule, are to be made 6-1/2 times their exterior diameter in length; and all other cases, that are to be filled in moulds, must be as long as the moulds, within a half of the interior diameter. Rocket cases, from the smallest, to 4 or 6 pounds, are generally made of the strongest sort of cartridge paper, and rolled dry; but the large sort are made of pasted pasteboard. (See observations on that subject.) As it is very difficult to roll the ends of the cases quite even, the best way is to keep a pattern of the paper for the different kinds of cases. These patterns should be longer than the case they are designed for, and the number of sheets required should be marked, which will prevent any paper being cut to waste. Cut the paper of a proper size, and the last sheet for each case, with a slope at one end; so that when the cases are rolled, it may form a spiral line round the outside; and that this slope may always be the same, let the pattern be so formed for a constant guide. Before you begin to roll, fold down one end of the first sheet so far, as that the fold will go two or three times round the former; then, in the double edge, lay the former with its handle off the table, and after rolling two or three turns, lay the next sheet on that which is loose, and roll it all on. The smoothing board, which is about twenty inches long, is now to be applied; and after rolling the paper three or four times, lay on, in the same manner, another sheet of paper, and smooth it in the same manner. This operation is to be repeated till the case is sufficiently thick. When the last sheet is rolled, we must observe, that the point of the slope is placed at the small end of the roller. The case being made, the small end of the former is put in, to about one diameter of the end of the case, and the end piece is inserted within a little distance of the former. Then give the pinching cord one turn round the case, between the former and the end piece. At first, pull easy, and keep moving the case, which will make the neck smooth, and without large wrinkles. This operation is called by the French _strangling_, or _choaking_. When the cases are hard to choak, let each sheet of paper (except the first and last in that part where the neck is formed) be a little moistened with water. Immediately after you have struck the concave stroke, bind the neck of the case round with small twine, which must not be tied in a knot, but fastened with two or three hitches.