But, previously, the value of steam, if employed in this direction, had occurred to the Marquis of Worcester, a nobleman of great ability and a quick imagination, who, for his loyalty to the cause of Charles I., had been confined in the Tower of London as a prisoner. On one occasion, while sitting in his solitary chamber, the tight cover of a kettle full of boiling water was blown off before his eyes; for mere amusement's sake he set it on again, saw it again blown off, and then began to reflect on the capabilities of power thus accidentally revealed to him, and to speculate on its application to mechanical ends. Being of a quick, ingenious turn of mind, he was not long in discovering how it could be directed and controlled. When he published his project--"An Admirable and Most Forcible Way to Drive up Water by Fire"--he was abused and laughed at as being either a madman or an impostor. He persevered, however, and actually had a little engine of some two horse power at work raising water from the Thames at Vauxhall; by means of which, he writes, "a child's force bringeth up a hundred feet high an incredible quantity of water, and I may boldly call it the most stupendous work in the whole world." There is a fervent "Ejaculatory and Extemporary Thanksgiving Prayer" of his extant, composed "when first with his corporeal eyes he did see finished a perfect trial of his water-commanding engine, delightful and useful to whomsoever hath in recommendation either knowledge, profit, or pleasure." This and the rest of his wonderful "Centenary of Inventions," only emptied instead of replenishing his purse. He was reduced to borrow paltry sums from his creditors, and received neither respect for his genius nor sympathy for his misfortunes. He was before his age, and suffered accordingly. * * * * * In 1698 his work was taken up by Thomas Savery, a miner, who, through assiduous labour and well-directed study, had become a skilful engineer. He succeeded in constructing an engine on the principle of the pressure of aqueous vapour, and this engine he employed successfully in pumping water out of coal mines. We owe to Savery the invention of a vacuum, which was suggested to him, it is said, in a curious manner: he happened to throw a wine-flask, which he had just drained, upon the fire; a few drops of liquor at the bottom of the flask soon filled it with steam, and, taking it off the fire, he plunged it, mouth downwards, into a basin of cold water that was standing on the table, when, a vacuum being produced, the water immediately rushed up into the flask.