The invention of bombs is said to be owing to Scotland, and to the siege of St. Andrews. In the Art of War (says the Anthologia Hibernica, vol. iii, p. 174) printed at Venice, we are shown the representation of a hogshead, coated with conical headed nails, in which there is enclosed a barrel of gunpowder, suspended in the centre by an iron tube, which communicates at both ends with the open air. This engine, we are told by the author, killed 558 persons by its explosion in the fosse.
Sec. XV. Of the Petard.
The petard is used to break down the gates and barriers of small towns, and even their walls, by hanging it against them, and setting fire to the fuse. Its invention is ascribed to the French Huguenots in 1579, who, by means of petards, took Cahors, in the same year. It was invented, as others inform us, by the celebrated Coehorn.
The petard is a hollow piece of iron, either cast or wrought, of the figure of a truncated cone, and usually eight inches high, and nine and a half inches diameter at the base, the metal being five-sixths of an inch thick at top, and half an inch at bottom. It is open at the large end; and the small end, which is rounded, is pierced with a hole, in which is placed a brass fuse, filled with composition, in lieu of which, however, an ordinary bomb-fuse, or a quick-match may be used. It is furnished with four trunnions, (one and a half inches by one), to receive the iron staples, that are attached to an oaken plank, eighteen inches square, and two and a half inches thick, and reinforced below by two iron bands, in the form of a cross, nailed and dove-tailed in. It has two iron handles to carry it by, and to hook it to a screw, fixed in the gate intended to be broken. It is filled with gunpowder.
When the petard is to be loaded, it is filled with powder to within three inches of the bottom. Some folds of cartridge paper are then put in, and a bed of tow well rammed. It is finished with a hot cement made of one part of rosin, and two parts of ground brick, or Spanish brown. A plate of iron four or five lines thick is set into this, that fits the inside of the petard at that part. It is furnished with three iron points, to be driven into the plank. A petard, ready for use, weighs eighty-five pounds, and contains nine pounds of powder.
Dimensions of the Petard.
According to Ruggeri, a petard is filled, after warming it, with three fingers of powder, which is moistened with brandy, and then compressed without crushing it. On this powder, a quick match is placed, which is also compressed; after which, it is filled with composition previously melted. The composition is as follows:
Composition for Petards.