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Fascinating Historical Physics Instrument – ’s Gravesande’s Ball and Ring with Oil Lamp (ca. 1875–1900)
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Physics demonstration instrument featuring a small oil lamp: the Ball and Ring of 's Gravesande, named after the Dutch physicist Willem Jacob 's Gravesande.
The 's Gravesande Ring is a classic apparatus for demonstrating thermal expansion of metals. It consists of a metal ball that fits through a metal ring at room temperature. When heated, the ball expands and no longer passes through the ring, illustrating the effect of heat on matter.
The base is cast iron, with a small oil lamp on top. This is likely the original lamp, as it fits precisely around the ring holder. I tested it: after heating for a while, the ball no longer fits through the ring, though it takes some time and the ball picks up soot in the process.
The ring can be unscrewed and moved up and down the central rod to position it around the ball.
The wick holder is marked with the letter R, "Brevete", and "Paris", suggesting French manufacture.
Exact age unknown, likely 1875–1900.
Total height: 28 cm
Ball diameter: 30 mm
