Calculations proving the comparative Economy of the Rocket Ammunition, both as to its Application in Bombardment and in the Field. So much misapprehension having been entertained with regard to the expense of the Rocket system, it is very important, for the true understanding of the weapon, to prove, that it is by far the cheapest mode of applying artillery ammunition, both in bombardment and in the field.

To begin with the expense of making the 32-pounder Rocket Carcass, which has hitherto been principally used in bombardments, compared with the 10-inch Carcass, which conveys even less combustible matter.

If the construction were more systematic, and elementary force used instead of manual labour, the expense of driving the Rocket might be reduced four-fifths, which would lower the amount to about 18s. each Rocket, complete; and if bamboo were substituted, which I am endeavouring to accomplish, for the stick, the whole expense of each 32-pounder Carcass Rocket would be about 16s. each.

Now as the calculation of the expense of the Rocket includes that of the projectile force, which conveys it 3,000 yards; to equalize the comparison, to the cost of the spherical carcass must be added that of the charge of powder required to convey it the same distance.

So that even with the present disadvantages of manufacture, there is an actual saving in the 32-pounder Rocket carcass itself, which contains more composition than the 10-inch spherical carcass, without allowing any thing for the difference of expense of the Rocket apparatus, and that of the mortar, mortar beds, platforms, &c. which, together with the difficulty of transport, constitute the greatest expense of throwing the common carcass; whereas, the cost of apparatus for the use of the Rocket carcass does not originally exceed £5; and indeed, on most occasions, the Rocket may, as has been shewn, be thrown even without any apparatus at all: besides which, it may be stated, that a transport of 250 tons will convey 5,000 Rocket carcasses, with every thing required for using them, on a very extensive scale; while on shore, a common ammunition waggon will carry 60 rounds, with the requisites for action. The difference in all these respects, as to the 10-inch spherical carcass, its mortars, &c. is too striking to need specifying.

But the comparison as to expense is still more in favour of the Rocket, when compared with the larger natures of carcasses. The 13-inch spherical carcass costs £1. 17s. 11½d. to throw it 2,500 yards; the 32-pounder Rocket carcass, conveying the same quantity of combustible matter, does not cost more than £1. 5s. 0d.—so that in this case there is a saving on the first cost of 12s. 11½d. Now the large Rocket carcass requires no more apparatus than the small one, and the difference of weight, as to carriage, is little more than that of the different quantities of combustible matter contained in each, while the difference of weight of the 13-inch and 10-inch carcasses is at least double, as is also that of the mortars; and, consequently, all the other comparative charges are enhanced in the same proportion.

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. 10s. 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 Rocket, it is distinctly seen; whereas, in ordinary projectiles it is scarcely to be traced—and hence has arisen a very exaggerated notion of the inaccuracy of the former.

But to recur to the economy of the Rocket carcass; how much is not the saving of this system of bombardment enhanced, when considered with reference to naval bombardment, when the expensive construction of the large mortar vessel is viewed, together with the charge of their whole establishment, compared with the few occasions of their use, and their unfitness for general service? Whereas, by means of the Rocket, every vessel, nay, every boat, has the power of throwing carcasses without any alteration in her construction, or any impediment whatever to her general services.

So much for the comparison required as to the application of the Rocket in bombardment; I shall now proceed to the calculation of the expense of this ammunition for field service, compared with that of common artillery ammunition. In the first place, it should be stated that the Rocket will project every species of shot or shell which can be fired from field guns, and indeed, even heavier ammunition than is ordinarily used by artillery in the field. But it will be a fair criterion to make the calculation, with reference to the six and nine-pounder common ammunition; these two natures of shot or shell are projected by a small Rocket, which I have denominated the 12-pounder, and which will give horizontally, and without apparatus, the same range as that of the gun, and with apparatus, considerably more. The calculation may be stated as follows:—

But this sum is capable of the following reduction, by substituting elementary force for manual labour, and by employing bamboo in lieu of the stick.

Now the cost of the shot or spherical case is the same whether projected from a gun or thrown by the Rocket; and the fixing it to the Rocket costs about the same as strapping the shot to the wooden bottom.

This 6s. 4½d. therefore is to be set against the value of the gunpowder, cartridge, &c. required for the gun, which may be estimated as follows:—

Taking the average, therefore, of the six and nine-pounder ammunition, the Rocket ammunition costs 3s. 2¾d. a round more than the common ammunition.

Now we must compare the simplicity of the use of the Rocket, with the expensive apparatus of artillery, to see what this trifling difference of first cost in the Rocket has to weigh against it. In the first place, we have seen, that in many situations the Rocket requires no apparatus at all to use it, and that, where it does require any, it is of the simplest kind: we have seen also, that both infantry and cavalry can, in a variety of instances, combine this weapon with their other powers; so that it is not, in such cases, even to be charged with the pay of the men. These, however, are circumstances that can in no case happen with respect to ordinary artillery ammunition; the use of which never can be divested of the expense of the construction, transport, and maintenance of the necessary ordnance to project it, or of the men exclusively required to work that ordnance. What proportion, therefore, will the trifling difference of first cost, and the average facile and unexpensive application of the Rocket bear to the heavy contingent charges involved in the use of field artillery? It is a fact, that, in the famous Egyptian campaign, those charges did not amount to less than £20 per round, one with another, exclusive of the pay of the men; nor can they for any campaign be put at less than from £2 to £3 per round. It must be obvious, therefore, although it is not perhaps practicable actually to clothe the calculation in figures, that the saving must be very great indeed in favour of the Rocket, in the field as well as in bombardment.

Thus far, however, the calculation is limited merely as to the bare question of expense; but on the score of general advantage, how is not the balance augmented in favour of the Rocket, when all the exclusive facilities of its use are taken into the account—the universality of the application, the unlimited quantity of instantaneous fire to be produced by it for particular occasions—of fire not to be by any possibility approached in quantity by means of ordnance? Now to all these points of excellence one only drawback is attempted to be stated—this is, the difference of accuracy: but the value of the objection vanishes when fairly considered; for in the first place, it must be admitted, that the general business of action is not that of target-firing; and the more especially with a weapon like the Rocket, which possesses the facility of bringing such quantities of fire on any point: thus, if the difference of accuracy were as ten to one against the Rocket, as the facility of using it is at least as ten to one in its favour, the ratio would be that of equality. The truth is, however, that the difference of accuracy, for actual application against troops, instead of ten to one, cannot be stated even as two to one; and, consequently, the compound ratio as to effect, the same shot or shell being projected, would be, even with this admission of comparative inaccuracy, greatly in favour of the Rocket System. But it must still further be borne in mind, that this system is yet in its infancy, that much has been accomplished in a short time, and that there is every reason to believe, that the accuracy of the Rocket may be actually brought upon a par with that of other artillery ammunition for all the important purposes of field service.

W. CONGREVE.