Glass Piercer

   Until the last few years of the nineteenth century, students explored the phenomena of physics at second-hand as they watched their instructors do demonstrations. The subject of electrostatics was particularly rich in demonstrations, many of them small variants of each other. One unique demonstration was the ability of the electric spark from a Leiden jar to piece a thin sheet of paper or metal, or even a thin sheet of glass. The object to be punctured was laid atop the glass cylinder, just touching the lower electrode. The upper electrode was then lowered, and the knob of the Leiden jar applied to the upper knob of the piercing apparatus.

   The two examples above are identical, apart from the finish on the wood bases. The one at the left is from Transylvania University, and the right-hand one is in the Garland Collection at Vanderbilt University. The apparatus is unmarked, but judging from the buying habits of the institutions, I suspect that it was made in France.

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