The fuse is used for setting off rockets and other varieties of fireworks, and also to communicate fire from one piece to another.
The material of the fuse is cotton thread. The size may be increased to any desired extent by repeated doubling of the thread. It should be soaked for a number of hours in vinegar, or, better still, in brandy. After it has absorbed sufficient of the liquid, powder is spread over it, and the cotton is worked, on the plate where it has been soaking, until it is thoroughly penetrated and completely covered by the powder paste. It is then taken from the plate and passed lightly through the fingers, in order to distribute the paste equally and to soften it. It is finally placed to dry in a shaded place.
When dry, the fuse is cut into pieces two and one-half feet long, after which it is wrapped up or boxed, and stored in a dry place.
The fuse used for communicating fire varies from one line in diameter to one and one-half lines, according to the size of the firework.
Grain powder is used for the priming. After it has been moistened with a little water, it is ground on a table with a wooden pestle, until it is reduced to a fine paste. It serves as a mastic to fasten and retain the fuse in the mouth of the ■rocket and elsewhere as required.