In like manner, the 42-pounder Carcass Rocket, which contains from 15 to 18 lbs. of combustible matter, will be found considerably cheaper in the first cost than the 13-inch spherical carcass: and a proportionate economy, including the ratio of increased effect, will attach also to the still larger natures of Rockets which I have now made. Thus the first cost of the 6-inch Rocket, weighing 150 lbs. and containing 40 lbs. of combustible matter, is not more than £3. 10_s._ that is to say, less than double the first cost of the 13-inch spherical carcass, though its conflagrating powers, or the quantity of combustible matter conveyed by it, are three times as great, and its mass and penetration are half as much again as that of the 10-inch shell or carcass. It is evident, therefore, that however extended the magnitude of Rockets may be, and I am now endeavouring to construct some, the falling mass of which will be considerably more than that of the 13-inch shell or carcass, and whose powers, therefore, either of explosion or conflagration, will rise even in a higher ratio, still, although the first cost may exceed that of any projectile at present thrown, on a comparison of effects, there will be a great saving in favour of the Rocket System. It is difficult to make a precise calculation as to the average expense of every common shell or carcass, actually thrown against the enemy; but it is generally supposed and admitted, that, on a moderate estimate, these missiles, one with another, cannot cost government less than £5 each; nor can this be doubted, when, in addition to the first cost of the ammunition, that of the _ordnance_, and _the charges incidental to its application_, are considered. But as to the Rocket and its apparatus, it has been seen, that the _principal expense_ is that of the first construction, an expense, which it must be fairly stated, that the charges of conveyance cannot more than double under any circumstances; so that where the mode of throwing carcasses by 32-pounder Rockets is adopted, there is, at least, an average saving of £3 on every carcass so thrown, and proportionally for the larger natures; especially as not only the conflagrating powers of the spherical carcass are equalled even by the 32-pounder Rocket, but greatly exceeded by the larger Rockets; and the more especially indeed, as the difference of accuracy, for the purposes of bombardment, is not worthy to be mentioned, since it is no uncommon thing for shells fired from a mortar at long ranges, to spread to the right and left of each other, upwards of 500 or even 600 yards, as was lately proved by a series of experiments, where the mortar bed was actually fixed in the ground; an aberration which the Rocket will never equal, unless some accident happens to the stick in firing; and this, I may venture to say, does not occur oftener than the failure of the fuze in the firing of shells. The fact is, that whatever aberration does exist in the