War vessels upon the plan of the Monitor speedily appeared among the navies of several nations. England refused at first to admit the value of the invention and was not converted until the double-turreted Miantonomoh visited her waters in 1866, when one of the London papers described her appearance among the British fleet as that of a wolf among a flock of sheep. The day of the big wooden war-vessels was over. It was, nevertheless, an Englishman and a naval officer, Captain Cowper Coles, who sought to deprive Ericsson of the honor of his invention. Coles declared that he had devised a ship during the Crimean War, in which a turret or cupola was to protect the guns. Ericsson's letter to Napoleon III., written in 1854, is sufficient answer to this, besides which Ericsson's scheme includes more than a stationary shield for the guns, which is all that Coles claimed. Coles succeeded, however, in inducing the British Admiralty to build a vessel according to his plans. This ill-fated craft upset off Cape Finisterre on the night of September 6, 1870, and went to the bottom with Coles and a crew of nearly five hundred men. Having devised an apparatus that made wooden war-vessels useless, Ericsson turned his attention to the destruction of iron-clads, and devoted ten years of his life to the construction of his famous torpedo-boat, the Destroyer, upon which he spent about all the money he amassed by other work. According to his belief, no vessel afloat could escape annihilation in a battle with his Destroyer. This vessel is designed to run at sufficient speed to overtake any of the iron-clads. It offers small surface to the shot of an enemy, and besides being heavily armored, it can be partly submerged beneath the waves. When within fighting distance it fires under water, by compressed air, a projectile containing dynamite sufficient to raise a big war-ship out of the water. The explosion takes place when the projectile meets with resistance, such as the sides of a ship. To Ericsson's great disappointment, the United States Government persistently refused to purchase the Destroyer or to commission Ericsson to build more vessels of her type. [Illustration: Development of the Monitor Idea.]