[42] It has been stated that Newcomen took out a patent for his invention in 1705; but this is a mistake, as no patent was ever taken out by Newcomen. It is supposed that Savery, having heard of his invention, gave him notice that he would regard his method of producing a speedy vacuum by condensation, as an infringement of his patent, and that Newcomen accordingly agreed to give him an interest in the new engine during the term of Savery’s patent. It will, however, be observed that the principle on which Newcomen’s engine worked was entirely different from that of Savery. Newcomen’s engine may be thus briefly described:--The steam was generated in a separate boiler, as in Savery’s engine, from which it was conveyed into a vertical cylinder underneath a piston fitting it closely, but moveable upwards and downwards through its whole length. The piston was fixed to a rod, which was attached by a joint or a chain to the end of a lever vibrating upon an axis, the other end being attached to a rod working a pump. When the piston in the cylinder was raised, steam was let into the vacated space through a tube fitted into the top of the boiler, and mounted with a stopcock. The pump-rod at the further end of the lever being thus depressed, cold water was applied to the sides of the cylinder, on which the steam within it was condensed, a vacuum was produced, and the external air, pressing upon the top of the piston, forced it down into the empty cylinder. The pump-rod was thereby raised; and the operation of depressing and raising it being repeated, a power was thus produced which kept the pump continuously at work. Such, in a few words, was the construction and action of Newcomen’s first engine. It will thus be observed that this engine was essentially different in principle from that of Savery. While the latter raised water partly by the force of steam and partly by the pressure of the atmosphere, that of Newcomen worked entirely by the pressure of the atmosphere, steam being only used as the most expeditious method of producing a vacuum. The engine was, however, found to be very imperfect. It was exceedingly slow in its motions; much time was occupied in condensing the contained steam by throwing cold water on the outside of the cylinder; and as the boiler was placed immediately under the cylinder, it was not easy to prevent the cold water from splashing it, and thus leading to a further loss of heat. To remedy these imperfections, Newcomen and Calley altered the arrangement; and, instead of throwing cold water on the outside of the cylinder, they surrounded it with cold water. But this expedient was also found inconvenient, as the surrounding water shortly became warm, and ceased to condense until replaced by colder water; but the colder it was the greater was the loss of heat by condensation, before the steam was enabled to fill the cylinder again on each ascent of the piston.