"When the marquis was a prisoner in the Tower of London, the tight cover of a kettle full of boiling water was blown off before his eyes; for mere amusement's sake he stuck 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 mehanical ends."- Page .

vered, 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. was before his age, and suffered accordingly.

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Savary added the use of a vacuum; Newcomen introduced the use of piston and cylinder, and condensation of the steam by the injection of cold water; Potter and Beighton made the engine open and shut its own valves. These three stages of improvement are all said to have been suggested by accidental circumstances. Savary happened to throw a wineflask, 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. Newcomen did not think of condensation by injection, till it was suggested by some water trickling into the cylinder through a hole which happened to have been worn in the piston. Potter was a little boy employed to open and shut the valves, which in turn let in water and steam, but being of rather a lazy disposition, and with a strong predilection for play, he fastened the handles of the valves by bits of string to some of the levers and cranks, which saved him all trouble in the matter. Beighton, the engineer, afterwards perfected the contrivance.

Properly speaking, Newcomen's engine, which was the most perfect of all those invented up to the time when Watt took up the subject, was not a steam, but an atmospheric engine; for though steam was employed, it formed no essential feature of the contrivance, and might have been replaced by an air-pump. All the use that was made of steam was to produce a vacuum underneath the piston, which was pressed down by the weight of the atmosphere, and raised by the counterpoise of the buckets at the other end of the beam. Watt, in bringing the expansive force of steam to bear upon the working of the piston, may be said to have really invented the steam engine. Half a century before the little model came into Watt's hands, Newcomen's engine had been made as complete as its capabilities ad