Having thus done, you must have a smooth board, about twenty inches long, and equal in breadth to the length of the case; in the middle of this board must be a handle placed length-ways; under this board lay your case, and let one end of the board lay on the table; then press hard on it, and push it forwards, which will roll the paper very tight; do this three or four times before you roll on any more paper: this must be repeated every other sheet of paper, till the case is thick enough; but if the rolling board be drawn backwards, it will loosen the paper: you are to observe, when you roll on the last sheet, that the point of the slope be placed at the small end of the roller. Having rolled your case to fit the mould, push in the small end of the former F, about one diameter from the end of the case, and put in the end piece 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; 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.
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.
To make Balóón Cases, or Paper Shells.
First you must have an oval former turned of smooth wood; then paste a quantity of brown or cartridge paper, and let it lay till the paste has quite soaked through; this done, rub the former with soap or grease, to prevent the paper from sticking to it; then lay the paper on in small slips, till you have made it one third of the thickness of the shell intended; having thus done, set it to dry, and when dry, cut it round the middle, and the two halves will easily come off; but observe, when you cut, to leave about one inch not cut, which will make the halves join much better than if quite separated; when you have some ready to join, place the halves even together, and paste a slip of paper round the opening to hold them together, and let that dry; then lay on paper all over as before, every where equal, excepting that end which goes downwards in the mortar, which may be a little thicker than the rest; for that part which receives the blow from the powder in the chamber of the mortar consequently requires the greatest strength: when the shell is thoroughly dry, burn a round vent at top, with square iron, large enough for the fuze: this method will do for balóóns from four inches two fifths, to eight inches diameter; but if they are larger, or required to be thrown a great height, let the first shell be turn’d of elm, instead of being made of paper.
For a ballóón of four inches two fifths, let the former be three inches one eighth diameter, and five inches and a half long. For a ballóón of five inches and a half, the diameter of the former must be four inches, and eight inches long. For a ballóón of eight inches, let the diameter of the former be five inches and fifteen sixteenths, and eleven inches seven eighths long. For a ten inch ballóón, let the former be seven inches three sixteenths diameter, and fourteen inches and a quarter long. The thickness of a shell for a ballóón of four inches two fifths, must be half an inch. For a ballóón of five inches and a half, let the thickness of the paper be five eighths of an inch. For an eight inch ballóón seven eighths of an inch. And for a ten inch ballóón, let the shell be one inch and one eighth thick.
Shells that are designed for stars only, may be made quite round, and the thinner they are at the opening the better; for if they are too strong, the stars are apt to break at the bursting of the shell: when you are making the shell, make use of a pair of calibers, or a round gauge, so that you may not lay the paper thicker in one place than another; and also to know when the shell is of a proper thickness; ballóóns must always be made to go easy into the mortars.