After some discussion with Calley, Newcomen entered into correspondence with Dr. Hooke, proposing a steam-engine to consist of a _steam-cylinder containing a piston similar to that of Papin's, and to drive a separate pump_, similar to those generally in use where water was raised by horse or wind power. Dr. Hooke advised and argued strongly against their plan, but, fortunately, the obstinate belief of the unlearned mechanics was not overpowered by the disquisitions of their distinguished correspondent, and Newcomen and Calley attempted an engine on their peculiar plan. This succeeded so well as to induce them to continue their labors, and, in 1705, to patent,[30] in combination with Savery--who held the exclusive right to practise surface-condensation, and who induced them to allow him an interest with them--an engine combining a steam-cylinder and piston, surface-condensation, a separate boiler, and separate pumps. [30] It has been denied that a patent was issued, but there is no doubt that Savery claimed and received an interest in the new engine. In the atmospheric-engine, as first designed, the slow process of condensation by the application of the condensing water to the exterior of the cylinder, to produce the vacuum, caused the strokes of the engine to take place at very long intervals. An improvement was, however, soon effected, which immensely increased the rapidity of condensation. A jet of water was thrown directly _into_ the cylinder, thus effecting for the Newcomen engine just what Desaguliers had done for the Savery engine previously. As thus improved, the Newcomen engine is shown in Fig. 19. Here _b_ is the boiler. Steam passes from it through the cock, _d_, and up into the cylinder, _a_, equilibrating the pressure of the atmosphere, and allowing the heavy pump-rod, _k_, to fall, and, by the greater weight acting through the beam, _i i_, to raise the piston, _s_, to the position shown. The rod _m_ carries a counterbalance, if needed. The cock _d_ being shut, _f_ is then opened, and a jet of water from the reservoir, _g_, enters the cylinder, producing a vacuum by the condensation of the steam. The pressure of the air above the piston now forces it down, again raising the pump-rods, and thus the engine works on indefinitely. [Illustration: FIG. 19.--Newcomen's Engine, A. D. 1705.]