When the surface lodes became exhausted, the necessity of employing some more efficient method of pumping the water became more and more urgent. In one pit after another the miners were being drowned out, and the operations of an important branch of national industry were in danger of being brought to a complete standstill. It was under these circumstances that Captain Savery turned his attention to the contrivance of a more powerful engine for the raising of water; and after various experiments, he became persuaded that the most effective agency for the purpose was the power of steam. It is very probable that he was aware of the attempts that had been previously made in the same direction, and he may have gathered many useful and suggestive hints from the Marquis of Worcester’s ‘Century;’ but as that book contained no plans nor precise definitions of the methods by which the Marquis had accomplished his objects, it could have helped him but little towards the contrivance of a practicable working engine.[27] [27] The absurd story is told by Dr. Desaguliers (‘Experimental Philosophy,’ ii. 465) that Savery, having read the Marquis’s book, “was the first to put in practice the raising of water by fire, which he proposed for the draining of mines;” and having copied the Marquis’s engine, “the better to conceal the matter, bought up all the Marquis of Worcester’s books that he could purchase in Paternoster-row and elsewhere, and burned ’em in the presence of the gentleman, his friend, who told me this!” It need scarcely be said that it was very unlikely that Savery should have attempted thus to conceal an invention recorded in a printed book which had been in circulation for more than forty years.