Considering first the conversion of the existing French navy, he examined and enlarged upon the various inefficiencies inherent in the usual disposition of ship armaments; in the manner in which the unit and the number of units of artillery force were selected for any individual design of ship; in the variety of the units, and in the lack of system observed in the various proportions between the gun, the charge and the projectile. He observed that the constant tendency of development, both in the French and in the English navy, was in the replacing of smaller by greater calibres, by which process the diversity of calibres was diminished and the effective force of the armament increased. Continuing this process, it appeared that the ideal armament would be reached, the maximum degree of force would be attained, when unity of calibre was achieved. When the calibre of the largest-sized cannon carried on the principal gun deck of ships-of-the-line was adopted as the sole calibre used, the maximum of force would be attained: the greatest possible destructive effect combined with the greatest possible simplification of means. These remarks applied equally to a solid shot and to a shell gun armament. If for some reason it were decided not to adopt shell fire, nevertheless it would be of advantage to re-arm the French sailing fleets on this principle, with guns of one calibre. M. Paixhans proposed as the unit the French 36-pounder. He explained the advantages to be derived from arming existing ships-of-the-line with 36-pounders all of the same calibre but of different weights on the respective decks. The guns on different decks would take different charges and would therefore project the shot with different muzzle velocities. They would be disposed, the heaviest on the lower deck; a lighter type (reamed out from 24-pounders) on the main deck; still lighter guns on the upper deck, and 36-pounder carronades on the quarter-deck and forecastle would complete the armament. The employment of solid shot was not favoured by him, however, and he claimed the results of various trials as showing the superior offensive value of shells, when compared with solid shot. Comparing a solid shot and a shell of the same external dimensions discharged with the same muzzle velocity, the former, he said, had only the advantage in superior range and penetrative power. The latter, while having a range greater than those at which sea actions were invariably fought and sufficient penetrative power to effect a lodgment in a ship’s timbers, required less powder to propel it, a lighter and therefore more rapidly worked gun from which to discharge it, and it had a destructive effect enormously greater than that of the solid ball.