The fuse is gradually filled with this composition, each proportion being well pressed in, without violence. Iron ramrods, fitted to the bore of the fuse are used for this purpose. Every time the materials are poured in, the ramrod is inserted, and by means of a small mallet, with which it is struck 14 or 15 times, the composition is pressed into a hard consistency.
When fuses have been well loaded, and the materials have previously been properly mixed, they will naturally burn with an equal steady fire, preserving in general an even length of flame, without spitting or irregularly shaking.
In order to preserve fuses for a length of time, the composition, when thoroughly prepared, must be covered with a mastick or cement made of ²⁄₃ds bees-wax and ¹⁄₃d rosin, well mixed together. Bomb fuses prepared in this manner, will burn either in water, or in earth, nearly 70 seconds, without being extinguished.
The usual method of priming fuses, is to grate about one third of a French inch of composition. Two small matches about 5 or 6 inches long, with the ends bent inwards, are then well fixed with pounded composition to the eye of the fuse, by which last operation it is completely filled and closed. This part is finally covered over with cartridge paper that is tied, and remains so till there is occasion to use it. Before the fuse is driven into the bomb, the thin or small end must be cut off, in order that the fire may be easily communicated to the mass of gun-powder, which is lodged in the bomb.
Fusees à bombes, à feu-mort, bomb fuses with dead light. There is a species of bomb-fuse, which is distinguished by the term feu mort, or dead-light. The difference between these fuses and the ordinary ones consists in this, that the eye instead of being pierced and hollow, is full and of a half spherical shape. In both cases, however, the composition is introduced through the small end.
The composition for fuses, à feu-mort, consists of 16 parts of pounded gunpowder and 9¹⁄₂ parts of ashes. The ashes must be baked over again, and run through a silk sieve. Potter’s earth or clay will produce the same effect as ashes.
In proceeding to charge a bomb-fuse that is made of ordinary wood, the eye, or aperture is first closed with pipe-clay, which is well beaten and pressed against the fuse in a small platter; the thin end of the fuse being held upwards. Three lines (or ³⁄₁₂ths of a French inch) of this earth will be sufficient to stop the communication of any fire. A tube, or trundle, filled with pounded gunpowder for the purpose of setting fire to the composition called feu mort, is thrust into the fuse, by which it is finally charged. If this charge of pounded gunpowder were to be omitted, the fuse might not be susceptible of ignition; but the quantity never ought to exceed 3 lines, as the fuse would split by the explosion.
When the grains of gunpowder have been well pounded, a trundle, or tube filled with the aforementioned composition must be applied, and it is finally loaded like the rest.
It must be recollected, that two inches of this composition will last as long as one of the quality with which common fuses are charged. Before the fuse is driven into the bomb, it must be pierced through with a gimblet of one line diameter, taking care, that the hole is made precisely through the charge of pounded gunpowder. One end of a priming match must be forced in, and three others be tied to it, which three are to fall upon the bomb when it lies in the mortar.
The particular object to be obtained from this sort of fuse, is to prevent the least trace of fire or light being visible in its projection; so that the enemy may remain ignorant of the range, or direction of the bomb, and not be able, of course, to get out of the way when it falls, or to avoid the effects of its explosion.