It is not possible, however, for a country desirous of maintaining its maritime supremacy to wait upon perfection in the manner implied as the policy of the parliamentary committee. Some drastic and immediate action was necessary, to redress the advantage accruing to France from the possession of the _Gloire_ and her sister frigates. Such action was duly taken; but before proceeding to examine this action it will be necessary to revert for a moment to a consideration of iron. We have already sketched the evolution of iron as a protective covering for warships; we must now glance back and briefly trace its progress as a constructive material. Iron vessels had appeared on the canals of England in the latter part of the eighteenth century. In 1815 a pleasure boat of that material had sailed on the River Mersey, attracting crowds of people whose credulity had been severely strained by the statement that an iron ship would float. Admiral Napier had manifested an early interest in iron ships; in 1820, in partnership with a Mr. Manby, he had constructed the first iron steamer, the _Aaron Manby_, and navigated it from London up the Seine to Paris, where in ’22 it attracted considerable attention. From this date onwards iron vessels increased in number. In ’39 the _Nemesis_ and _Phlegethon_ were built by Mr. Laird for the East India Company, and in the China war of ’42 these gunboats played a conspicuous and significant part. The grounding of the _Nemesis_ in ’40 on the rocks of Scilly afforded early evidence of the value of watertight bulkheads (a Chinese invention) when embodied in an iron hull. As the size of ships increased, the disabilities attaching to the use of timber became more and more evident. Though braced internally by an elaborate system of iron straps, knees, and nutted bolts in iron or copper, the large timber-built ship, considered as a structure, was fundamentally weak; in fact the presence of the straps and ties contributed in no small degree to its inability to withstand continuous stress. The fastenings did not accord with the materials which they fastened together, and the wood was relatively so soft that when a severe strain arose a general yielding took place, the boltheads sinking into the wood and causing it to give way to the pressure thrown locally upon it. As tonnage increased the metal fastenings grew more and more conspicuous, the ship became a composite structure of wood and iron, with the result that uniformity of elasticity and strength was lost and the stresses, instead of being distributed throughout the structure, tended to become localized at certain points. “The metallic fastenings of a timber-built ship act to accelerate her destruction so soon as the close connection of the several parts is at all diminished.” So in 1840 wrote Augustin Creuze, a graduate of the disbanded school of naval architecture and one of the most gifted and eminent men of his profession at that day.