229. For chambered guns the sponges must fit the chambers and slopes, and a portion of the main bore, as shown in the drawings furnished by the Bureau. When made of wool, the whole surface is covered, and so sheared as to have no windage, and to be even with the points of the worm, that they make take effect. The heads for woollen sponges should be one inch less in diameter than the bores or chambers of the guns for which they are intended.
In future, sheepskins will not be allowed, but covers for sponge-heads made up ready to slip over the head and be tacked on.
230. The heads for the sponges of unchambered guns are to be eight inches long; and all sponge-heads intended to be covered with woollen material must be slightly tapered and secured by a thin copper hoop, fastened with copper tacks, on the inner end.
231. For Bristle Sponges the heads must be 1.5 inch less in diameter than the bores or chambers for which they are designed. The bristles are to be sheared so as to work easily and leave no windage. The worm must project one-fourth of an inch, in order to take the bottom of the bore, and special care is to be taken by the Inspector that it has both the necessary stiffness to act efficiently and elastically enough, when pressed home, to yield sufficiently to allow the bristles to act also. Spiral spaces extending the whole length of the sponge-head, including the portion adapted to the main bore in chambered guns, are to be left, in order to bring out the unconsumed portions of cartridges. These spaces must be left-handed like the worm.
Great care is necessary, in stowing them, to prevent the bristles from being crushed down by contact with hard substances. For this purpose fenders will be provided with copper tacks, on the inner end.
One will be allowed to each division, for each calibre, for cleaning guns.
232. Sponge-staves are to be made of tough ash, 1.75 inch in diameter, and must be 18 inches longer than the bores of the guns for which they are intended.
233. Sponge-caps are made of duck, and, except for spar-deck guns where they are exposed to the weather, should not be painted, but they, as well as the staves, should be kept clean by scrubbing. A becket should be attached to the end to haul them off by.
Sponges should be washed carefully and dried after use before putting the caps on, and frequently examined and dried to prevent their rotting.
ROBINSON'S WORM.