Vacuum Pump
Pneumatics
<p><strong>A vacuum pump is a device that removes gas from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke. This 19th century pump is made of brass.<br /></strong></p>
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Fountain in a Vacuum
Pneumatics
<p><strong>"The “Fountain in Vacuo” is a perfectly delightful and entertaining 19th century demonstration that is never done today. Volume 1 of Pike’s Illustrated Catalogue of Optical, Mathematical and Philosophical Instruments (New York, 1856) describes it, “The fountain consists of a tall receiver, of glass, about five inches wide in the swell, but contracted at the top, and cemented by a neck at the lower end to a brass cap, having within a jet pipe attached to a stop-cock, which screws into the cap; the whole is mounted on a stand when not in use. To use, the fountain is connected with the air pump by means of the stop-cock and tube; after the air is exhausted out of the receiver, the cock is shut to prevent its return; then the whole is unscrewed from the plate of the receiver, and the lower end of the tub is immersed in a vessel of water; on opening the stop-cock, the pressure of the atmosphere on the surface of the water in the vessel having not counterpoise from the interior of the cylinder, forces up the fluid through the jet-pipe with considerable velocity, which forms a pleasing jet-d’eau, or fountain in vacuo. Price $4.50; larger $5.00”.</strong></p>
<p><strong>from: Thomas B. Greenslade, Jr., "Demonstrations With a Vacuum: Old Demonstrations For New Vacuum Pumps", The Physics Teacher, <span style="text-decoration:underline;">27</span>, 332-341 (1989)<br /></strong></p>
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Buoyancy of Air
Pneumatics
<strong>Chemists, and other people who do careful weighings, know that we live at the bottom of a sea of air, and that a buoyant force equal to the weight of the air displaced by our bodies acts upward on us. Alas, the density of air is small, and the buoyant force is also small. To demonstrate this effect, a brass balloon is placed on one end of an equal arm balance. When the air surrounding the balloon is removed, the buoyant force is removed, and the balance tilts.</strong>
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Magdeburg Hemispheres
Pneumatics
<p><strong>The Magdeburg hemispheres are a pair of large copper hemispheres with mating rims. When the rims were sealed with grease and the air was pumped out through the valve below the lower hemisphere, the lowered pressure within the sphere made it very difficult to pull the spheres apart: a famous image shows teams of horses pulling in opposite directions unable to part the spheres. This device was designed by German scientist Otto von Guericke in 1650. von Guericke was also the mayor of Magdeburg, thus the device name. This device is still used as a teaching tool to demonstrate the force of air pressure. This version was made by Pike in New York.<br /></strong></p>
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Bladder Glass
Pneumatics
<strong>This is a device used to demonstrate the effect of atmospheric pressure. A glass vessel with openings at the bottom and top has its large top opening covered by a piece of animal bladder that is tied to seal it around its edges. As air is pumped from the vessel through the bottom opening, atmospheric pressure causes the bladder to deform downward, ultimately bursting with a loud bang. This seemingly simple effect is mentioned in the majority of nineteenth century physics textbooks.</strong>
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