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|Hauksbee's Air Pump
An air pump is a device for extracting air from a vessel to produce a partial vacuum. Early pumps had been developed by Robert Boyle and others, but the one built by Francis Haucksbee was such an improvement over those earlier designs that his pumps were said to be the best in the world.
Francis Hauksbee first demonstrated his "New Invented Air Pump" at a meeting of the Royal Society in London in December 1703. His demonstration so captivated the members of the Society that they soon appointed him official demonstrator at all their meetings. In 1709, he used the device to illustrate his book Physico-Mechanical Experiments on Various Subjects.
The principle of Hauksbee's device is very similar to that of a bicycle pump, adapted to suck rather than blow. The experimental apparatus is placed in the vacuum vessel at the top, which is connected by a narrow tube through valves to the base of two cylindrical barrels. When the handle (center of picture) is turned clockwise, a rack-and-pinion mechanism raises the piston in the left-hand barrel, drawing air from the vessel down into the barrel. At the same time the right-hand piston moves down, expelling the air inside it which had been drawn out of the vacuum vessel on the previous stroke. After a few turns clockwise the direction of the handle must be reversed and the process repeated, with the two barrels exchanging roles. The whole cycle must be repeated until the degree of vacuum in the vessel, indicated by a mercury barometer, reaches the required level.
A wide variety of apparatus was available for use with the pump. Hauksbee himself studied the way electrified objects behave in a vacuum, and found that a spinning glass globe, with the air pumped out from inside it, gives out a purple glow when rubbed with the hand. Future experiments using variations of Hauksbee's pump led to the discovery of X-rays and the electron, as well as to development of the television picture tube.
Library >> Technology >> Mechanical Engineering and Machinery >> Vacuum Technology
This page was last updated on June 20, 2017.