Thus the cylindrical case is made, and the former must now be withdrawn while it is damp, as, if suffered to remain till dry, the paper would contract so much as to r ender that impossible. By fastening a loop round the head of the former, or passing a pin through it, a firm hold is secured for it on the table, and the case is then to be taken of by the hands.
It is now ready for choking should it be a rocket or a wheel-case. This also must be done while it is damp ; and if it has been a thy tolled case, it is neces sary that one end should be damped for this purpose. Small cases may easily be choked by the hand; but for larger ones a machine is necessary. This however is very simple, and may be attached to the rolling table. Plate CCCCIAXII. Fig. 4. At the lower end of one of the legs of this, there is a foot lever or treddle moving on a hinge. A strong twisted cord of hemp, or what is better, of gut, is attached to it ; and, ascending up to the table, passes over a pulley which is attached to it at the edge. Beyond this it is fixed to the table, so that there is an interval in which the cases for choking may be placed. The cord is sufficiently loose when the lever is up to admit of its making one turn round the case, and the length is easily regulated where it is fastened to the table.
The former which had been withdrawn, for the put pose of being assured that it can come out, must now be introduced again to within about a diameter, or somewhat more, of the extremity which it is intended to choke The subsidiary piece with its wire, which was formerly mentioned, is then introduced at the end, so that half a diameter may remain between it and the former, which is occupied by the intermediate wire. Being then placed within one turn of the pinching cord, the lever is pressed down by the foot, and the case is rolled backwards and forwards through the turn of the cord, till the artist is satisfied that the wire is closely pinched. After this is done, a piece of strong twine is wound round the furrow thus made, and secured by three half hitches and some paste, or pasted paper or glue. The ends of the case are then to be cut smooth and even while it still lies on the former ; and that near the choke is to be cut in such a manner, that it may have a hemispherical cup exactly equal to half a diameter of the interior. The former and its piece
may then be withdrawn, that the artist may be satis fied that the first of these is• still loose, and the wet case is then to be introduced into the driving mould on the nipple only. By then restoring the former, and giving two or three slight blows to it, the mouth of the case is rendered smooth and even. The spindle must then he passed through for the purpose of smoothing the vent hole, and bringing it back to its proper size ; or, if it is a rocket case, the hollow rammer and spindle may be used at once, to give the whole of the parts about the vent their true shape and size.
There are some cases, stch as those of tourbillons, that require to have both ends closed ; and it is conve nient to close one of them, at least, in the choking en gine. This is easily done by introducing a plug of damp pasted paper, and then pinching the choking rope close round it. Other cases, such as portfires, Roman candles, Ste. that are to fire from an open month, may be closed at the end in the same manner, as may the cases for crackers and serpents. Such ends in the larger works may be still farther secured by a coating of clay driven on them within.
The cases for illumination lights, or speckies, are made of thin paper, rolled on formers, of diameters va rying from two to five-eighths of an inch, and tneir lengths vary from two to six inches. These also are pinched close at one end. Such cases only require three or four rounds of paper, and the last one, at least, should be pasted.
•ortfire cases, as well for the lighting fireworks as for military service, must be made strong with pasted pa per, and the interior diameter, or that of the composi tion, may be about half an inch. The exterior one is about six-eighths, and these cases must be from twenty inches to two feet in length, The length of cases for rockets, according to their several diameters, will be found hereafter in the table of proportions for these ; and, with respect to other fires, they will be more con veniently mentioned when these fireworks come under review.