followed, and the material began to come into use elsewhere. In 1837 the Rainbow, of 600 tons, by far the largest iron steamer which had yet been built, was laid down at Birkenhead. It will thus be seen how bold was the step taken by Mr. Brunel when, in 1838, he advised the Great Western Company to use iron as the material for their new ship, which was to be of the startling size of 3,443 tons displacement. Nor were his innovations to stop with size and material. On his earnest recommendation to the company it was decided, in 1839, to change from the first design of the usual paddle-wheels to a screw. [Illustration: Ericsson’s First Arrangement of Underwater Propeller (Oct. 10, 1834). Ericsson’s Propeller (July 13, 1836). Smith’s Amended Specification (May 18, 1839). Smith’s Specification (May 31, 1836). Cammerow’s Specification (Dec. 10, 1828). Specifications of Early Patents taken out in England.] Three years before (in 1836), a Swede, whose name was destined to become much more famous in our own land, had successfully shown the practicability of screw propulsion, in the Francis B. Ogden, on the Thames. “She was 45 feet long and 8 feet wide, drawing 2 feet 3 inches of water. In this vessel he fitted his engine and two propellers, each of 5 feet 3 inches diameter” (Lindsay). She made ten miles an hour, and showed her capabilities by towing a large packetship at good speed. There was no question of the success of this little vessel, which was witnessed on one occasion by several of the lords of the admiralty. Notwithstanding her unqualified success, Ericsson had no support in England. It happened, however, that Commodore Stockton, of our navy, was then in London; and witnessing a trial of the Ogden, ordered two small boats of him. One, the Robert F. Stockton, was built, in 1838, of iron, by Laird—63 feet 5 inches in length, 10 feet in breadth, and 7 feet in depth. She was taken—April, 1839—under sail, to the United States by a crew of a master and four men. This little vessel was the forerunner of the famous Princeton, built after the designs of Ericsson, who had been induced by Commodore Stockton to come to America as offering a more kindly field for his talents. In the same year with Ericsson’s trial of the Ogden, Mr. Thomas Pettit Smith took out a patent for a screw; and it was by the company formed by Smith that the screw propeller was first tried on a large scale, in the Archimedes, of 237 tons, in 1839. Of course the names mentioned by no means exhaust the list of claimants to this great invention. Nor can it be said to have been invented by either of these two, but they were the first to score decisive successes and convince the world of its practicability.