In the early ’sixties the guns chiefly in use on this side of the Atlantic were the 9-inch gun, weighing 12 tons, and discharging a 250-lb. shot with 43 lb. of powder, the initial velocity being 1,730 feet per second. The largest gun was the 23½ tons, with a 12-inch diameter, its shot weighing 600 lb. and the charge of powder 70 lb., and the muzzle velocity being 1,240 feet per second. The larger guns could not be worked without considerable improvements being made in the ships themselves. Greater height had to be given between the decks, and the distances between the guns had also to be increased, there being 25 feet between the centre lines of the ports for the 12-ton guns, while the 23-ton guns required about 30 feet between the ports and between 8 and 9 feet between the deck and the underside of the beams supporting the deck above. To keep the portholes as small as possible an arrangement was made whereby the gun should be pivoted near the muzzle. The later developments in naval artillery began with the 12-inch 46-ton wire gun, which was the chief weapon of the battleships between 1894 and 1897. This gun was 37 feet 1 inch in length, or 35.43 calibres, and threw an armour-piercing shell of 850 lb. with a charge of 167½ lb. of cordite. It had a muzzle penetration of 36.8 inches of wrought iron, and was in every respect as powerful as the 13½-inch 67-ton gun, which it replaced. During 1898, the 12-inch wire gun, weighing about 50 tons, was introduced. The adoption of breech-loading made possible a very rapid rate of firing, even with the heaviest guns. In 1881, the Government, in reply to an invitation it issued for guns to meet certain requirements, received a number of replies from gun-making firms, as did also the French Government at about the same time in reply to a similar invitation. These guns, which became known as quick-firing or rapid-firing guns, were comparatively small weapons, and the Armstrong Company at Elswick, having improved upon them with quick-firers of 4.7 inches and 6 inches calibre, they were adopted throughout the Navy as the secondary armament. Their superiority over those they displaced was such that a battery’s firing power was increased sixfold. An important trial took place on board the _Hardy_ in 1887, when a 4.7 gun was mounted on a centre pivot recoil mounting, the whole weighing 4 tons 12 cwt.; this gun fired ten rounds in less than 48 seconds. Compare this with the firing of the ordinary 5-inch breech-loading gun on the gunboat _Mastiff_, when ten rounds took 6 minutes 16 seconds.