We find, also, that two modes are used for discharging the mortars. The one consists in having a communication from without to the bottom of the cone, which contains the powder, and applying the match to this vent, on the same principle as that for firing a cannon, or common mortar. The other, by firing a quick-match in the conical cavity, and putting in the charge with the balloon; letting the match, however, be of a sufficient length to come out of the mouth of the mortar, and fall over its side. This match, when fired, will communicate fire to the powder in the cone, and produce the same effect. Metallic cylinders, and especially copper, however small, are certainly preferable to those made in the usual manner.
Sec. IV. Of making Balloon Fuses.
Wood, particularly beech, is generally employed for forming fuses, which is turned of the shape required. If made with pasted paper, they will answer for the purpose of fire-works. The diameter of the former for fuses for coehorn balloons must be half an inch; for a republican fuse, five-eighths of an inch; for an eight-inch fuse, three-fourths of an inch; and for a ten inch fuse, seven-eighths of an inch. Having rolled the cases, pinch and tie them almost close at one end; then drive them down, and let them dry. Before they are filled, mark on the outside of the case, the length of the charge required, allowing for the thickness of the bottom; and when the composition is rammed in, take two pieces of quick-match about six inches long, and lay one end of each on the charge, and then a little meal-powder, which is to be rammed down loose. The loose ends of the match, double up, and place in the top of the fuse. This top must be covered with a proper cap to keep it dry. When the shells are put into the mortars, uncap the fuses, and pull out the loose ends of the match, and let them hang on the sides of the balloon. The use of the match is to receive the fire from the powder in the chamber of the mortar, in order to light the fuse. When the shell is put in the mortar, its fuse must be uppermost, and exactly in the centre. Some meal-powder is usually sprinkled upon it.
Fuses of wood are longer than those of paper, and not bored through, but left solid about 1/2 an inch at bottom; so that, when used, this end is cut off. They are sawed, however, at a proper length, measuring the charge from the cup at top. On the subject of Fuses, see [the last part] of the work.
Fuses for bombs, Morel remarks, are formed of five thicknesses of paper, or of pasteboard, made of that thickness; and the former, on which the fuse case is rolled, should be one-third diameter. The composition is put in with a spoon, and each charge is driven with twenty strokes of a moderate size mallet.
Composition for the fuses of bombs or balloons.
| 1. | Meal powder, | 12 oz. | |
| Sulphur, | 4 — | ||
| Charcoal, | 6 — | ||
| 2. | Saltpetre, | 1 lb. | 10 — |
| Sulphur, | 8 — | ||
| Meal powder, | 1 lb. | 6 — | |
| 3. | Saltpetre, | 1 lb. | 8 — |
| Sulphur, | 8 — | ||
| Meal powder, | 1 lb. | 8 — |
Sec. V. Of the Mosaic and Common Tourbillon.
The tourbillon de feu of the French, or whirlwind of fire, is the same as the soleil montant; because it ascends in full illumination, and scatters fire in various directions. The tourbillon, therefore, receives its name from the effect it produces. It raises itself very high, and forms a whirl of fire and terminates in two coronal figures, or crowns, which descend in what are called parasols. It does not, however, produce crowns, except when it is charged with Chinese fire.
There are two kinds of tourbillons, which we will describe, namely, the mosaic and the common. The mosaic produces a tail of some length, and after whirling round, finishes with a report. This effect is owing to its particular structure and formation, as it differs from the common tourbillon. In preparing the cases for mosaic tourbillons, pasteboard, formed of five sheets of paper, is used. They are made seven inches in length upon a roller or former 5/12ths of an inch in diameter. Their thickness, when rolled, is 1/8th of an inch. They are choaked in the usual manner, and the excess of the string is cut off. After having put a quarter of an inch of earth into a case, and beating it with ten or twelve blows with the mallet, we mark the height of the earth on the outside of the case. We then load it to the height of 7/12ths with the composition heretofore mentioned. Another quarter of a spoonful of earth is then put in. We then choak, and bind the case in this place. Two fingers of grain powder are now added; we again choak, and bind it above this. We put in the same composition, after the last operation, to the height of 7/12ths of an inch. The choaking, it is to be observed, must not wholly close the case; so that the composition can set fire to the powder.