ARTIFICIAL Flfcfc-WORKS. *f and cylinder together. 8. The roller. 3. The rammer. 4. The shortef rammer. It is to be observed, that some of these moulds are made nine diameters of their orifice long; the shell therefore,- with the wart, will be twelve diameters. These sort of rockets fiy very high, because of their length, containing a greater chargft thrfn the short; nevertheless, the piercer1 needs to be no longer than seven diameters, but substan- tial, so as to keep in its proper attitude:—it will requird the dimension of rw«-thirds of the diameter at bottom; and from thence, tapering, to half the diameter. o To prepdfe Cases for Swarmers, or Rockets. THE cases, or trunks, of rockets, are made of different sorts of things, viz. paper, wood, tin, pasteboard, linen, leather, &c. In paper cases, which are for the most part made use of, it must be observed, l.That great care ought to be taken in winding, or rolling them, upon the roller, right and close. 2. That the concave stroke be struck clean, smooth, and without large wrinkles: and, 3. That each sort of cases be of an equal length and size, The rocket-shells being very tiresome for two persons to make by hand, a machine has been invented for the ease- ment, ft is made of art oaken board, about two foot wide, and three or four inches thick, planed smooth, and cut out into channels, or groves, of different sizes, to serve for greater, or lesser, rockets; and is commonly called the1 saddle. To these sort of saddles are also made pressers, whereby the cases on the roller are pressed down with a heawy hand; the handle of the roller having a hole in the middle, a small iron bar is put in, and as the man presses' with one hand, he turns the roller with the other; and,- by this means, the paper is brought as tight as it ought to be. See fig: 5 and 6. For four and six pound shells it is to be obscrvefd, that each