JAMES WATT'S STEAM ENGINE

     James Watt was born in 1736 at Greenock. After his apprenticeship in London he returned to Glasgow and worked within the precincts of Glasgow College. There he happened to repair a Newcomen engine. He observed that when every time water was injected to condense the steam in the cylinder it chilled the cylinder too. The next admission of steam had to reheat the cylinder. Naturally this was the cause of the poor efficiency of Newcomen engine.

     Watt developed an ingenious method to overcome this problem. Condensing of the steam was done in a separate vessel which was always kept cold and maintained vacuous by means of a air pump. The cylinder itself was surrounded by a steam jacket to maintain its temperature. After overcoming some problems regarding workmanship and tools the first viable steam engine was made in 1780. Later he made many more improvements in steam engine like converting the rectilinear movement of the piston and beam into a rotational movement of the shaft, and developing a “double-acting” engine in which steam was admitted to side of the piston in turn. He also invented a sculpting machine which was earlier called “the likeness lathe”.

NEWCOMEN ENGINE

After Savery’s invention the next major innovation in vintage steam engine was made by Thomas Newcomen. (1663-1729). He combined the three simple notions of balance, condensing of steam to produce vacuum and the piston working in a cylinder. 

Steam was inducted in a cylinder at a pressure  little above that of the atmosphere with a weighted beam counterbalancing it and drawing up the piston. Cold water is then sprayed to condense steam. The partial vacuum created forces the piston down reversing the tilt of the beam raising the load.

 As the machine works owing to the pressure of atmosphere these vintage models were known as atmospheric engines.  Before the commercial production of Newcomen Engine the early vintage models were manually operated. The machines were primarily used in the mines of Midland and Cornwall. However owing to the high level of wastage of fuel in these vintage machines, it was used only in mines extracting low-grade coal.

EARLY STEAM ENGINES

                Steam power and steam engines are normally associated with James Watt and George Stephenson. But the story of harnessing power from steam goes long back. Much earlier than inventors like Savory (a military engineer) Newcomen (a blacksmith) Calley (a glazier), Potter (an engine boy) and Smeaton (the builder of Eddystone lighthouse)

                The earliest pioneers were Egyptians and Greeks who were aware of the power of steam and its properties. The first attempt in harnessing the power of steam was by Hero a mathematician. He developed a device using steam power to open the giant doors of Greek temples.

                Hero’s method was ingenious. Fire burning in a hollow alter expands and its pressure and drives the water kept in a bucket beneath the alter. The increased weight makes the bucket to descend thereby pulling a pair of vertical posts on which the doors are pivoted. This action opens the door of the temple. 

                Hero’s invention inspired a host of people notably Branco an Italian in 1547 and Solomon de Caus in 1615. The latter inventors helped in raising water much higher than its source

defying gravity. This was probably the first steam pump.

                But the real spurt in innovation was the contribution of Denis Papin and Thomas Savery in 1698 .Savery invented a new machine which according to his own words was useful for ‘raising of water and occasion motion to all sorts of mill work’.It resembled Papin’s machine and depended on the condensation of steam generated in a separate vessel. Steam was admitted to the condenser alternatively displacing the water it contained and driving it through check valves up a discharge pipe.