These large Rockets have from their weight, combined with less diameter, even more penetration than the heaviest shells, and are therefore equally efficient for the destruction of bomb proofs, or the demolition of strong buildings; and their construction having now been realized, it is proved that the facilities of the Rocket system are not its only excellence, but that it actually will propel heavier masses than can be done by any other means; that is to say, masses, to project which, it would be scarcely possible to cast, much less to transport, mortars of sufficient magnitude. Various modifications of the powers of these large Rockets may be made, which it is not necessary here to specify. The 42 and 32-pounders are those which have hitherto been principally used in bombardment, and which, for the general purposes of bombardment, will be found sufficient, while their portability renders them in that respect more easily applied. I have therefore classed them as medium Rockets. These Rockets will convey from ten to seven pounds of combustible matter each; have a range of upwards of 3,000 yards; and may, where the fall of greater mass in any particular spot is required, either for penetration or increased fire, be discharged in combinations of three, four, or six Rockets, well lashed together, with the sticks in the centre also strongly bound together. The great art of firing these _fasces of Rockets_ is to arrange them, so that they may be sure to take fire contemporaneously, which must be done either by priming the bottoms of all thoroughly, or by firing them by a flash of powder, which is sure to ignite the whole combination at once. The 42 and 32-pounder Rockets may also be used as explosion Rockets, and the 32-pounder armed with shot or shells: thus, a 32-pounder will range at least 1,000 yards, laid on the ground, and armed with a 5½-inch howitzer shell, or an 18 and even a 24-pounder solid shot. The 32-pounder is, as it were, the mean point of the system: it is the least Rocket used as a carcass in bombardment, and the largest armed either with shot or shell, for field service. The 24-pounder Rocket is very nearly equal to it in all its applications in the field; from the saving of weight, therefore, I consider it preferable. It is perfectly equal to propel the cohorn shell or 12-pounder shot. The 18-pounder, which is the first of the _light_ natures of Rockets, is armed with a 9-pounder shot or shell; the 12-pounder with a 6-pounder ditto; the 9-pounder with a grenade; and the 6-pounder with a 3-pounder shot or shell. These shells, however, are now cast expressly for the Rocket service, and are elliptical instead of spherical, thereby increasing the power of the shell, and decreasing the resistance of the air.