| The apparatus at the left is is "Ritchie's Illustration
of the Hydraulic Press; mahogany base with a sliding platform supported
by brass pillars, with a weight; upon the base is placed a bellows-shaped
rubber bag, connected by a tube to a globular bag fitted with a cap and
cork. Fill the globe with water, and elevate it; the pressure of the column
will force the water into the bellows, raising the weight; lower the globe,
and the weight will force the water back into it... $12.00".
Middlebury College's surviving example of this apparatus is in remarkably good condition after one hundred and more years. It needs only the replacement of rubber parts to make it work once more.
| This version of the hydrostatic paradox at the right
was in storage at the museum at the United States Military Academy at West
Point when I saw it in February 2000.
The same apparatus, shown at the left, was on display in the Garland Collection of Classical Physics Apparatus at Vanderbilt University when I visited it in March 2001.
The apparatus is listed in the 1865 Deleuil catalogue as a device to show that all liquid-filled columns exert pressure independently of each other. The apparatus cost 40 francs, or $10.00.
Today I would fill each column with a liquid of a different density, with water filling the central column and reservoir. The taps would then be slowly opened, and liquids added to keep the interfaces at the same level.
REFERENCE: Thomas B. Greenslade, Jr., "Nineteenth Century Textbook Illustrations (XXII), The Hydrostatic Paradox". Phys. Teach., 16, 228-229 (1978)