At last a start made on a Steam Section. Many Water pumps of this type (Beam Engine) worked all over the world some still in preservation in Cornwall. Used in the draining tin mines.

Grateful thanks to Francesco for allowing the use of his Watt animation see more on steam power at his really good quality web site http://www.oocities.org/Athens/Acropolis/6914/index.htm

The final version of the new Watt engine worked in 1778, and it consumed 1/3 of the steam that the Newcomen engine used.
This engine worked a crossbeam for pumping. The cylinder was closed (by a cap) and heated by a warm steam jacket. The condenser, positioned underground, was cooled and vacuum operated (by a pump).
When the piston reached the top of its stroke the exhaust-valve opened and a partial vacuum was produced below the piston (inside the cylinder communicating to the condenser).
Above the piston, at the same time, the entrance of steam helped the atmospheric pressure to drive the piston down. On this stroke the crossbeam raised water in the pump. When the piston reached the bottom of the stroke the inlet valve closed and an equilibrium valve opened to allow steam to pass from above to below the piston. The engine piston (now with the same pressure above and below) was driven up by the crossbeam and the descent of the very, very heavy pump piston and rod. Note the presence of the condenser and the warm steam jacket that surrounds the cylinder.

Watt's Engine

     It was Scottish inventor James Watt who invented the first engine that ran solely on steam. It was also he who improved the steam engine greatly, setting the basic design for today’s modern engines. His engine was much more efficient than Newcomen’s and used only ¼ the amount of fuel.
     Watt found that a lot of the steam generated was used to reheat the piston cylinder after it was cooled by the cold spray of water. He solved the problem by creating a separate condenser so the piston cylinder would always remain hot saving a lot of steam. Since steam was elastic it would rush to the vacuum created in the separate condenser. To keep the piston hot Watt sealed the cylinder using steam to push down the piston in the place of air pressure. Saving even more steam, steam was only injected into the cylinder for a fraction of the stroke, which continued through the expansion of the steam.
     Later with his double acting engine he doubled his machines power. The final version of the Watt engine did not use a vacuum to bring down the piston but used steam to push the piston both ways. Steam was let out to one side of the piston pushing it the other way. The piston is connected to a slide valve that controls the openings to the cylinder. When the piston reaches the end of its cycle the valve opens on the other side pushing it back and allowing exhaust steam to go out the blast pipe. The process is repeated, sometimes when the steam expands too much it could condense to water rusting the steel cylinder.
     At Watt’s time there was not the sufficient skill to wrought boilers and cylinders that could withstand the power of high-pressure steam so his engines were never very powerful. It was Richard Trevithick in later years who started using high pressure steam with the double acting engine and installing it in locomotives.