This 6_s._ 4½_d._ therefore is to be set against the value of the gunpowder, cartridge, &c. required for the gun, which may be estimated as follows:-- £. _s._ _d._ 6-pounder Amm’n. {Charge of powder for the 6-pounder 0 2 0 {Cartridge, 3½_d._ wooden bottom, 0 0 7¼ { 2½_d._ and tube, 1¼_d._ ------------- £0 2 7¼ ------------- £. _s._ _d._ 9-pounder Amm’n. {For the 9-pounder charge of powder 0 3 0 {Cartridge, 4½_d._ wooden bottom, 0 0 8¼ { 2½_d._ and tube, 1¼_d._ ------------- £0 3 8¼ ------------- Taking the average, therefore, of the six and nine-pounder ammunition, the Rocket ammunition costs 3_s._ 2¾_d._ 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.