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Piston and cylinder
In science, the piston and cylinder is a mechanical device for either creating a vacuum or containing a volume of fluid capable of expansion or contraction through the action of heat. The piston and cylinder, pictured adjacent, was invented by German engineer Otto Guericke in about 1647 for the purposes of proving the existence of vacuums in nature. [1]Thermodynamics
The piston and cylinder, together with the vacuum pump, also invented by Guericke, led to the formulation of the various gas laws, beginning with the work of Robert Boyle and Robert Hooke, as formulated in Boyle's law (1662), culminating later in the ideal gas law (1834), the design of the first steam engine by French engineer Denis Papin (1690), the first working steam engine by English engineer Thomas Savery (1698), and the initiation of thermodynamics as a subject, in 1824, by French engineer Sadi Carnot, in his Reflections on the Motive Power of Fire, a treatise on heat engines in general.
History
To visually show the effect of a vacuum, in efforts to disprove Greek philosopher Aristotle's c. 350 BC supposition that "nature abhors a vacuum", in the late 1640s German engineer Otto Guericke designed a piston and cylinder, as labeled adjacent, and conducted various demonstrations to demonstrate its power of the weight of the atmosphere. The air cylinder a was about twenty-inches high and fifteen-inches wide, having its sides perfectly even and parallel, which could be fixed firmly in a vertical position by the ring s. The piston, p, q, r, was made to fit exactly inside of the cylinder, p being of iron and q wood, and the rounded head r, formed of hard oak, had a grove on its edge which was filled with flax or hemp.
To demonstrate the power or strength of the vacuum, the piston was let into the cylinder, and its iron handle was passed through the ring of the arm o, shown below, in such a manner that it could move freely up and down through the whole height of the cylinder and at the same time be preserved in a straight line. In a first experiment, the piston was positioned at the bottom of the cylinder the stop-cock x was closed. In this arrangement, the joint efforts of twenty or more men could not raise the piston more than halfway up. The men, in effect, were not just pulling on the piston, but the weight of a column of atmosphere 62-miles high. [1]
References
1. (a) Wilson, George. (1849). “On the Early History of the Air-Pump in England”, The Edinburgh New Philosophical Journal, (pgs. 330-54).
(b) Galloway, Robert L. (1881). The Steam Engine and its Inventors. London: MacMillan and Co.
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Latest page update: made by Sadi-Carnot
, Jan 20 2009, 12:10 AM EST
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