And so we come to the construction of the _Great Britain_, of which the model is illustrated opposite page 126. Let us recollect that it was only in 1836 that the little six-ton launch _Francis Smith_ had been built, and that it was only three years later that the _Archimedes_ showed by her successful voyages that the screw method of propulsion was no fanciful, impracticable theory. In this same year, 1839, there began to be built a still more wonderful screw steamer. The Great Western Steamship Company had already been so satisfied with the _Great Western_ that they believed that a far larger ship would be even still more profitable. Therefore, Brunel was again consulted, and he reported that already the furthest limit of long ships built of wood was reached. There was no alternative but to construct her of iron, for the reasons that I explained some time since. Iron had already been used in ship-building for barges and also for steamboats, but on no large scale. Aaron Manby, in conjunction with Charles Napier, had built the first iron steamboat as far back as 1821. This ship had been conveyed in sections from Horseley, where she was made, to the Surrey Canal Dock, and there put together. After being tried on the Thames on May 9th, 1822, she steamed away the next month with Napier in command, and Manby as engineer, arriving in Paris on the eleventh of the same month. She was thus not merely the first iron steamship, but the first iron ship that ever put to sea. For the next twenty years she continued to ply on the Seine. Napier was the financier of the attempt to promote iron steamers on the French river, but by 1827 the slump in the steamboat had taken an acute form, and he was left a comparatively poor man. But in 1832 the _Lady Lansdowne_ was built by John Laird of Birkenhead for the City of Dublin Steam Packet Company, and she was the first iron steamer constructed with the intention of performing sea-service. She was a paddle-boat, and measured 133 feet long, 17 feet wide, with a tonnage of 148 and a nominal horse-power of 90. Later still the _Robert F. Stockton_, to which we have alluded, was also of iron.