The Brazilian Government began a series of experiments in 1871 which convinced them that better guns were produced in this country than on the Continent. The Bessemer steel process was improved by Sir Joseph Whitworth for gun-making, and having adopted breech-loading guns, he obtained results superior to those obtainable with any form of muzzle-loading weapon. The Brazilian Government gave permission for him to offer to lend to the British Admiralty a 7-inch breech-loading steel gun he had made for the former, and a 35-ton muzzle-loading gun, in order that comparative tests might be made, but the British Government declined; it had no love for breech-loaders. Having produced a type of gun capable, as he believed, of penetrating any armour then in existence, Sir Joseph Whitworth set about producing an armour-plate which should be able to beat the gun. Using his compressed steel, he invented what he called “impregnable armour-plating,” built in hexagonal sections, each of which was constructed of a series of concentric rings arranged round a central circular disc, this method preventing a crack caused by the impact of a projectile from passing beyond the ring in which it occurred. A Palliser shell of 259 lb. fired from a 9-inch gun with a charge of 50 lb. of pebble powder, which would have smashed an ordinary 12-inch iron armour-plate, was itself smashed against this new armour, and the target itself was forced 18 inches back into the sand and was only slightly dented. A great deal of reliance was placed in America on the gun invented by Mr. Rodman, after whom it was named. Several of the American monitors were armed with these weapons. One, bought by the British Government and tested at Shoeburyness, weighed 19 tons and had a smooth bore 15 inches in diameter, and fired a round shot of 453 lb. with a charge of 100 lb. of American powder. It pierced the 8-inch plates of the _Warrior_ type of target, but as in other experiments it was less successful, the Americans claimed that it was used in such a way as not to show its full capabilities. Even if it had been, it could only have had a very short career, as the breech-loading gun was steadily making its way in foreign navies, and any form of smooth-bore muzzle-loader, whether American or English, would have proved singularly ineffective against ships carrying rifled breech-loaders. The Mackay gun, an English invention doomed to early supersession, was an attempt to combine the simplicity of the smooth-bore with the penetrating force of the rifled gun, and in experiments made with this weapon on the _Agincourt_ target, in 1867, the gun fully demonstrated its usefulness. [Illustration: HEAVY GUN UNMOUNTED.] [Illustration: 6-INCH B.L. 50-CALIBRE GUN COMPLETED AND WITH MOUNTING. _Photographs supplied by the Coventry Ordnance Works, Ltd._]