A System of Pyrotechny / Comprehending the theory and practice, with the application of chemistry; designed for exhibition and for war.

by James Cutbush

The author of the Œuvres Militaires, tom. xxii, p. 222, speaking of the infernal machine, observes, that, if he were to be in a situation, which required the use of so dreadful an explosion, especially to destroy a bridge, he would prefer having the machine made simply with different strong pieces of wood, joined together, so as to be in the shape of an egg, or of a cone reversed.

The whole must then be made compact with cords twisted round. This method, in his opinion, is not only the best, but can be executed in the most easy and expeditious manner. He further adds, that, in order to burn or blow up wooden bridges, and even to destroy such as are constructed upon arches, several sorts of barges or boats might be used, which should be filled with fire-works, bombs, petards, &c. It would, likewise, be easy to construct these machines upon floating rafters, carrying several thousand pounds weight of gunpowder, which might be confined within strong pieces of wood, put together in the manner already described.

These machines should be piled one above another, and long iron bars must be thrown across the floats, or be fixed like masts; so that, when the whole of the combustible material is beneath the centre of the bridge, the rafters may be stopped. Great care must be taken to dispose the matches in such a manner, that no fire may be communicated to the gunpowder before the machine reaches the exact spot, which is to be destroyed.

In 1804, an infernal machine was used at Boulogne, which is described as follows:

This machine appears to be as simple in its construction, as it is calculated to be effectual in its operations. It is composed of 2 stout planks, 17 feet long, which form its sides, and are distant from each other about 7 feet.

These planks are connected by transverse timbers, screwed to the planks; so as to keep the whole firm and compact, and to prevent the danger of their being separated at sea. Of these transverse timbers, two are at the fore extremity, and three behind. This may be called, the frame or hull of the machine; the remainder of the work, being either for the stowage of the combustible matter, or for the accommodation of the seamen, who row the machine. Along the transverse timbers, at both extremities, are laid parallel to the sides, five longitudinal bars of nearly the same strength as the transverse timbers, which form a kind of grate, on which the coffers, containing the combustible matter, are placed. The grate behind is double the size of the one before, on the principle of giving facility to the motion of the whole, by making the machine lighter at the head. In the centre, between the planks forming the sides, from the inner extremity of the grate behind, to the outer extremity of the grate before, there is fixed a plank, somewhat broader than the side planks, which is well secured to them by three stout transverse timbers, which pass under the centre plank, to prevent its giving way to pressure.

In this plank, two triangular apertures are cut for men who row, to dispose of the lower extremities, whilst they ply the machine. Their seats, however, are so contrived, that each man's pressure is directly over that part of the plank, which is supported by the transverse timbers. The seats lie nearer to the head than to the hind part of the machine; perhaps to be some counterpoise for the greater weight of the combustible matter behind. Near each seat are fastened by rings to the sides, two oars, one on each side, and each man plies a pair. When the machine is worked to its destination, the men set the combustibles in a train for explosion, and abandon their posts.

The whole is so regulated, as to weight of materials, that the machine floats, or, more probably, moves under the surface of the water; so that little more than the heads of the men are seen. This secures the men and the machine from the fire of the enemy; and as the oars must be constantly plied under water, there is less danger of their being discovered by their noise, as they approach.

Infernal machines have also been made, to be used on land. Such is the machine we are told, which was intended for the destruction of Bonaparte. They may be made to explode at a given time, by clock-work, or by a match, calculated to burn a certain time!