The almost unlimited supply of labour-power in the steam-engine came at a time when the existing supply of manual labour was proving utterly inadequate to cope with the demands of the manufacturer. This was especially the case in textile fabrics. In its earlier stages the manufacture of cotton had been retarded by the difficulty with which the weavers obtained a sufficient supply of cotton yarn from the spinsters; and this difficulty became yet greater when the invention of the fly-shuttle enabled one weaver to do in a single day what had hitherto been the work of two. The difficulty was solved by a Blackburn weaver, John Hargreaves, who noticed that his wife's spindle, which had been accidentally upset, continued to revolve in an upright position on the floor, while the thread was still spinning in her hand. The hint led him to connect a number of spindles with a single wheel, and thus to enable one spinster to do the work of eight. Hargreaves's invention only spurred the wits of a barber's assistant, Richard Arkwright, to yet greater improvement in the construction of a machine for spinning by rollers revolving at different rates of speed; and this in its turn was improved and developed in the "mule" of a Bolton weaver, Samuel Crompton. The result of these inventions was to reverse the difficulty which hampered the trade, for the supply of yarn became so rapid and unlimited as to outrun the power of the hand-loom weaver to consume it; but a few years after the close of the American war this difficulty was met by the discovery of the power-loom, which replaced the weaver by machinery. Ingenious however as these inventions were, they would have remained comparatively useless had it not been for the revelation of a new and inexhaustible labour-force in the steam-engine. It was the combination of such a force with such means of applying it that enabled Britain during the terrible years of her struggle with France and Napoleon to all but monopolise the woollen and cotton trades, and raised her into the greatest manufacturing country that the world had seen.