PYROTECHNY. 







tech- In making cases, both paste and glue are required ; 

 "> but the first is chit-fly wanted. Paste for thi.i p; 

 \****^S must be ni.ule .-is thick as it is for the use or book- 

 binders and shoemakers. It is usual to put ro-,in into 

 it, which serves no purpose unless it bo that of pre- 

 serving it longer without moulding. Alum, whi 

 also commonly introduced, is of very little use, except 

 as it may render the cases somewhat less combustible ; 

 and glue, if it is in sufficient quantity to have ai: 

 feet at all, only serves to render it intractable. To 

 keep it from moulding, a little oil of turpentine is the 

 most effectual substance, and a small quantity of cor- 

 rosive sublimate prevents rats and mice and cockroaches 

 from destroying the fireworks when they are to be 

 stored away for any time. 



Spherical Cases. 



Sj)herical These are only required for paper shells, and they 

 casfg. arc t o be rnade in the spherical former already describ- 



ed. Being fixed in its stand, which is to form the fuse 

 hole, it must first be soaped that the paper may come 

 off easily when the shell is finished. The paper must 

 then be cut into stripes, which ace to be laid to meet 

 round it in various circles like the great circles in a 

 sphere. Other pieces being afterwards laid on in gores 

 till the former is covered, the work may proceed with 

 rapidity until it has acquired the requisite thickness, 

 which may vary from half an inch upwards according 

 to the size of the shell. But it must not be so far 

 completed upon the former but that it may still admit 

 of more coats after it has been removed. Being thus 

 brought up to a sufficient size, it must be suffered to 

 dry in its place, when it is to be cut into two hemi- 

 spheres by a saw well greased, and removed from the 

 block. After this, by pasting on a few more coats of 

 paper, the hemispheres are secured, and the shell 

 brought up to the required strength and size. Care 

 must, be taken that it be made thus strong enough to 

 bear the explosion of the mortar, as there is no fear 

 but that it will be split by the bursting charge which 

 it is to contain. 



Cylindrical Cases. 



Cylindrical These are of various kinds, and require some dif- 

 cases. ferences in the management, while they all demand 

 considerable attention. The cases fur small spiral or 

 firewheels as they are called, must be made by rolling 

 the paper round a wire, which is slightly greased or 

 soaped. Two or three turns of paper, according to its 

 strength, are sufficient for these, as if they are too 

 thick, they will either break in the turning or burst in 

 the firing. The last turns must be pasted, but with 

 as thin and little paste as possible, for the same rea- 

 sons, and the paper ought to be parallel, so that the 

 case throughout may be of an equal thickness. The 

 cases for leaders to conduct quick match must be made 

 in the same way ; but the paper for these should be of 

 a much thicker quality, that it may bear rough handling 

 and bending, as well as the paint with which these 

 must generally be covered. In the wheel cases, lengths 

 from fifteen to eighteen inches are sufficient; but those 

 for leaders may be made of all imaginable lengths, as 

 they are required for so many different purposes. 



In making rocket or other cases that are required to 

 fit closely in the moulds, it is proper to ascertain first 

 by trial what length of paper is necessary to make the 

 case of the requisite thickness. Thus all risk of waste 

 or error is avoided, which is important when there is 



much work to be done. The paper in then to be cut i>rdurlt- 

 to the rei.uikite size, taking care to have it a little too "? 

 large in that direction which corresponds to the dia- v ^r > y^*' 

 r of the case, that there may be an allowance for 

 irregularity at the ends which is unavoidable in 

 rolling. At one of the other bides which correspond 

 to the length of the case, the paper must be carefully 

 cut at right tingles ; that when it i rolled, the line 

 within may be parallel to the axis, without which the 

 rammer may by hold of the edge, and force it down 

 in driving. This is an accident carefully to be avoid- 

 eel, as it may spoil the effect of a firework altogether. 

 On the opposite bide of the paper, the cut is made 

 oblique at an angle of ten or twelve degrees ; to that, 

 when rolled up, the edge forms a spiral round the case 

 of about one turn. The wider part being placed at 

 tiie bottom, is secured by the string which forms the 

 clioak ; and thus the case is tight at the outer joint, 

 and does not unfold in driving or otherwise. If the 

 case is so thick that more sheets of paper than one are 

 necessary, al' except the last may have both the longi- 

 tudinal sides parallel. 



In making up the cases a flat smooth table is re- 

 quired, with a rolling board, which may be about a foot 

 and a half or two feet broad, and which must at any 

 rate exceed the length of the case. It is furnished 

 above with a handle, by which it may be easily held. 

 In pasting the paper, it is better that the last or inner- 

 most turns should remain dry, because if wetted, or if 

 any paste adheres to the former, it will be difficult to 

 withdraw it. When pasted it is laid near the edge of 

 the table, and the formfr is laid in it with its handle 

 beyond the table. The case is then rolled up as well 

 as can be done by hand, and then it must be placed 

 under the rolling board. By pressing hard on this, 

 and continuing to roll the case thus pasted on the table, 

 it can be condensed to a great degree of firmness ; but 

 care must be taken always to roll in one direction, or 

 if that were reversed, the paper would be loosened, 

 and the case be rendered spungy. This operation is 

 completed by the addition of as much paper as may be 

 necessary to bring it to the requisite thickness. 



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 render 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 off 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 dry rolled 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. 

 PlateCCCCLXXII.fig.4. At the lower end of oneof the p LATI 

 legs of this, there is a foot lever or treddle moving on a CCCCLXXII. 

 hinge. A strong twisted cord of hemp, or, what is better, Fig. 4. 

 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 Conner which had been withdrawn, for the pur. 



