The machine, for boring rockets, is similar, in some respects, to a lathe. The rocket is confined in a box, and, by means of a wheel, which is made to turn a second one, an auger rammer is put in motion. The rammer must be of a size, proportionate to the rocket, and of the same diameter, as the top of the bore intended, and continue of that thickness, a little longer than the depth of the bore required. The thick end of each _rammer_ must be made square, and all of the same size. The rammer is made to move backward, and forward, so that, after the rammer is marked three and a half diameters of the rocket, from the point, set the guide, allowing for the thickness of the front of the rocket box, and the neck and mouth of the rocket. When the rocket is fixed in the box, it must be pushed forward against the rammer, and, when the scoop of the rammer is full, draw the box back, and knock out the composition. A little oil is sometimes used, to prevent the friction from setting fire to the rocket. Having bored a number of rockets, taps must be used. These taps are similar to the common spicket. When employed, it is necessary to mark them three and a half diameters from the point, allowing for the thickness of the rocket's neck. There are several contrivances for the boring of rockets. The operation is sometimes done, by confining the rocket in a box, and boring it with a borer, fixed in a brace, using, at the same time, a proper director. This brace is like the common _brace_, used by carpenters, or formed on that principle, and made of iron. The motion, given by the hand, performs the operation. _Sec. V. Of the Preservation of Steel or Iron Filings._ When treating of iron, we mentioned, that it has the property of oxidizing rapidly, when exposed to the air and moisture; and that its effects in fire-works, in that case, would be either destroyed, or considerably diminished. And even fire-works, in which iron enters as a component part, will, if kept long, lose some of their effect, in consequence of the change, which the iron suffers; for, instead of producing brilliant sparks, which is their intention, it would impart a dull red appearance. Two methods are recommended for the preservation of iron. The one is to melt a portion of sulphur, and throw the filings into it, and afterwards to separate the extraneous sulphur. The other consists in wrapping them up in oiled paper. As to the first method, we may apprehend the effect of the sulphur, combining with some of the iron, instead of coating it, forming thereby a sulphuret, which, besides, is readily decomposed by the contact of air and moisture, producing sulphate of iron. The second method, of wrapping them in oil, or, in fact, covering them with oil, is certainly a greater preventive from rust, for where the oil is in contact, no oxidizement can take place.