Plate 3, Fig. 1, represents a sub-division of Rocket Cavalry, or Rocket Horse Artillery, marching in column of threes. It consists of six sections, of three men in each, or a less number of sections, according to the whole strength of the troop, followed by four ammunition horses, each pair led by a driver riding between them; on the full scale, therefore, a sub-division will consist of 24 horses and 20 men, and will carry into action 152 rounds of 12-pounder Shell or Case Shot Rockets, and six bouches a feù or chambers, carried by the centre men of each section. Fig. 2 represents this division in action, where the division may be supposed to have been halted in line, on the words--“_Prepare for action in front--dismount_”--Nos. 1 and 3 having dismounted, and given their leading reins to No. 2, who remains mounted, No. 1 runs forward about 15 or 20 paces with the chamber, which he draws from the leather case at the back of No. 2’s valise; and while Nos. 2 and 3 are preparing a Rocket, drawn from any one of the holsters most convenient, No. 1 fixes the chamber into the ground, pointing it to the desired object, and lights his portfire ready for the first round, which No. 3 by this time will have brought to him, and laid into the chamber; there remains, then, only for No. 1 to touch the vent of the Rocket with his portfire, No. 3 having run back for another round, which No. 2 will have been able to prepare in the mean time. In this way the sub-division will, without hurry, come into action with six bouches a feù, in one minute’s time, and may continue their fire, without any extraordinary exertion, at the rate of from two to three rounds from each chamber in a minute, or even four with good exertion; so that the six bouches a feù would discharge 80 rounds of 6-pounder ammunition in three minutes. Twelve light frames for firing the 12-pounder Rockets at high angles are further provided in addition to the ground chambers, and each of the drivers of the ammunition horses has one in his charge, in case of distant action. The preparation of the Rocket for firing is merely the fixing the stick to it, either by the pincers, pointed hammer, or wrench, provided for joining the parts of the stick also. These modes I have lately devised, as being more simple and economical than the screw formerly used; but cannot at present pronounce which is the best; great care, however, must be taken to fix the stick securely, as every thing depends on it; the vent also must be very carefully uncovered, as, if not perfectly so, the Rocket is liable to burst; and in firing the portfire must not be thrust too far into the Rocket, for the same reason.