This form of cut-off motion is still a very usual one, and can be seen in nearly all steamers in the United States not using the device of Sickles. It was at about this time, also, that Stevens, having succeeded his father in the business of introducing the steam-engine in land-transportation, as well as on the water, adopted the use of steam expansively on the locomotives of the Camden & Amboy Railroad, which was controlled and built by capital furnished principally by the Messrs. Stevens. He at the same time constructed eight-wheeled engines for heavy work, and adopted anthracite coal as fuel. In the latter change he was thoroughly successful, and the same improvement was made with engines built for fast traffic in 1848. The most remarkable of all the applications of steam-power proposed by Robert L. Stevens was that known as the Stevens Steam Iron-Clad Battery. As has already been stated, Colonel John Stevens had proposed, as early as 1812, to build a circular or saucer-shaped iron-clad, like those built 60 years later for the Russian Navy. Nothing was done, however, although the son revived the idea in a modified form 20 years afterward. In the years 1813-'14, the war with England being then in progress, he invented, after numerous and hazardous experiments, an _elongated shell_, to be fired from ordinary smooth-bored cannon. Having perfected this invention, he sold the secret to the United States, after making experiments to prove their destructiveness so decisive as to leave no doubt of the efficacy of such projectiles. As early as 1837 he had perfected a plan of an iron-clad war-vessel, and in August, 1841, his brothers, James C. and Edwin A. Stevens, representing Robert L., addressed a letter to the Secretary of the Navy, proposing to build an iron-clad vessel of high speed, with all its machinery below the water-line, and having submerged screw-propellers. The armament was to consist of the most powerful rifled guns, loading at the breech, and provided with elongated shot and shell. In the year 1842, having contracted to build for the United States Government a large war-steamer on this plan, which should be shot and shell proof, Robert L. Stevens built a steamboat at Bordentown, for the sole purpose of experimenting on the forms and curves of propeller-blades, as compared with side-wheels, and continued his experiments for many months. After some delay, during which Mr. Stevens and his brothers were engaged with their experiments and in perfecting their plans, the keel of an iron-clad was laid down in a dry-dock which had been constructed for the purpose at great cost. This vessel was to have been 250 feet long, of 40 feet beam, and 28 feet deep. The machinery was designed to furnish 700 indicated horse-power. The plating was proposed to be 4-1/2 inches thick--the same thickness of armor as was adopted 10 years later by the French for their comparatively rude constructions.