My Science School

The invention of the steam engine during the eighteenth century had a fundamental effect on man’s progress. Some earlier forms of this machine had appeared during the previous century. The most famous were those of papin whose work provided a great stimulus for research into steam.

Papin built a boat with steam operated paddles, but builders of sailing boats were hostile to this new craft and papin could not make much progress with it. However, he had proved what a powerful force steam could be in locomotion. Thomas newcomen built a steam engine in 1705. It began to be used for pumping water out of mines about six years later, and by 1725 the engine was widely used in collieries. It continued in use for many years although it was not very efficient and worked slowly. It was James watt (1736-1819) who examined all the previous efforts and perfected them into a steam engine that worked fast and efficiently. For this engine watt invented a steam condenser that was separate from the cylinder which worked the piston.

The steam engine had a sensational success and proved itself enormously useful, especially in factories where it replaced machines that had previously been worked by water or animal power. It was eventually used as a locomotive to pull wagons.

 

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Thomas Edison had discovered in his experiments that there were certain bodies through which electric power flowed more easily. He called these good conductors and other bodies that resisted the flow of electric power he called bad conductors. When electricity tried to travel along a bad conductor the latter would resist so much that it glowed until became white-hot.

A carbon filament, for example, gave out a good deal of light; but the light did not last very long because the carbon would soon burn itself up as it was in contact with the oxygen in the air.

Edison then carried out an experiment inside a glass bulb from which he had removed all the air. This time the light of the glowing filament lasted much longer and the fist electric light bulb was born.

Carbon filaments have now been replaced by tungsten wire as its high melting point, low rate of evaporation and low electrical consumption make it most suitable for use in light bulbs. A further improvement has been the introduction of an inert gas in to the bulb. This was at first nitrogen but is now a mixture of 88 per cent argon and 12 per cent nitrogen.

 

Picture Credit : Google