The blowing-powder scoops, having been laid at A, B, &c., all that is required is to turn the bowl or platter, a little round to the left, and they will come in rotation, ready for the next case. Also, by putting the scoop, fig. 10, alternately to the left and right of the scoop, fig. 12, it will always be known whether the proper quantity of fuse has been put in.
Coloured stars, from their fierceness, have a tendency to burn in the cases. This defect may be remedied by putting upon each star a small scoopful of Starting Fire, No. 1, before putting in the interval fuse; as much as will fill round the sides of the star. This composition is somewhat fiercer than would suit for the regular fuse, so catches the blowing-powder sooner.
A roman candle is well charged when the stars isochronise, or come out at equal intervals of time: they should, also, theoretically, ascend to equal heights; but, with coloured stars, this cannot be perfectly insured, as some shrink more than others in drying, and, of course, fit more loosely; some are heavier, some fiercer than others.
The interval fuse must always be driven in at twice, never at once. Each star, with its blowing-powder and fuse, occupies about an inch and a half; perhaps a trifle more.
Instead of driving in clay at the bottom, plaster of paris may be used, and then the foot, fig. 9, will not be required. Have some plaster of paris in a wide-mouthed bottle; a glass of cold water with a salt-spoon in it; and a number of pieces of paper, about 4 inches square. Put a small quantity of the plaster on one of the pieces of paper; indent the middle with the finger; put to it a little water, and work it up with a dessert-knife. Just as it gets to the consistency of mortar, and is about to set, mould it with the fingers, to the shape of a cork; push it into the end of the case; rest the case on a flat surface; insert the rammer, and give it two or three slight jolts; turn it round a few times, and withdraw it. If the plaster sticks to the end of the rammer, it shows, either that you have used the plaster too wet, or have not turned the rammer round a sufficient number of times.
No more plaster must be mixed at a time than will suffice for one case. When plaster has once set, it cannot be mixed up a second time; therefore take a fresh piece of paper, and let the knife be cleaned every time. It is advisable to have two dessert-knives, then one can be used with which to scrape the other. As much plaster should be used as will fill the case up about 1⁄2 an inch. They must be set by to dry; their not requiring the use of the foot will be found a great convenience.
Roman candles are usually made from 3⁄8 to 6⁄8; but 5⁄8 is a very satisfactory size. If a roman candle is intended to be fired singly, twist a piece of touchpaper round the mouth. If the cases are intended to be fired in threes, fours, &c., to form a bouquet, or to be placed round a mine, jack-in-the-box, or devil-among-the-tailors, omit the touchpaper, and envelope the case in double crown, made to project an inch beyond the mouth, to receive the leader, or quickmatch.
A steel-pen inserted, nib backwards, in the end of a small paper tube, rolled round the end of a penholder, makes a neat little scoop. It may be fastened in with a little plaster of paris. A scoop may also be made with a quill.
Cracks in wooden bowls may be stopped with the same material; and, if painted over with linseed oil, after getting dry, will remain waterproof for a long time. A screw may be made to hold in brickwork, by drilling a hole in the brick, and pushing in the screw, covered with plaster.