Having thus pinched and tied the case so as not to give way, put it into the mould without it’s foot, and, with a mallet, drive the former hard on the end piece, which will force the neck close and smooth; this being done, cut the case to its proper length, allowing from the neck to the edge of the mouth half a diameter, which is equal to the height of the nipple; then take out the former, and drive the case over the piercer with the long rammer, and the vent will be of a proper size. Wheel cases must be drove on a nipple with a points in order to close the neck, and make the vent of the size required; which, in most cases, is generally one fourth of their interior diameter: as it is very often difficult, when the cases are rolled, to draw the roller out, you may make a hole through the handle, and put in it a small iron pin, by which you may easily turn the former round, and pull it out. Fig. 17. shews the method of pinching cases; P a treddle, which, when pressed hard with the foot, will draw the cord tight, and force the neck as close as you please; Q a small wheel or pully, with a groove round it for the cord to run in. Cases are commonly rolled wet, for wheels and fixed pieces; and when they are required to contain a great length of charge, the method of making those sort of cases is as follows: Your paper must be cut as usual, only the last sheet must not be cut with a slope; having your paper ready, paste each sheet on one side, then fold down the first sheet as before directed, but be careful that the paste does not touch the upper part of the fold, for if the roller be wetted, it will tear the paper in drawing it out: in pasting the last sheet, observe not to wet the last turn or two in that part where it is to be pinched, for if that part be damp, the pinching cord will stick to it, and tear the paper; therefore, when you choak those cases; roll a bit of dry paper once round the case, before you put on the pinching cord; but this bit of paper must be taken off after the case is choaked. The rolling board, and all other methods, according to the former directions for the rolling and pinching of cases, must be used to these as well as all other cases. To make Tourbillon Cases. Those sorts of cases are generally made about eight diameters long, but if very large, seven diameters will be sufficient: tourbillons will answer very well from four ounces to two pound, but when larger there is no certainty. The cases are best rolled wet with paste, and the last sheet must have a streight edge, so that the case may be all of a thickness: when you have rolled your cases, after the manner of wheel cases, pinch them at one end quite close; then, with the rammer, drive the ends down flat, and afterwards ram in about one third of a diameter of dryed clay. The diameter of the former for these cases must be the same as for sky rockets. N. B. Tourbillons are to be rammed in moulds without a nipple, or in a mould without its foot.