Scientific Medical & Mechanical Antiques
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U.S. Patent No. 411689, Sept 24, 1889
C.C. Smith & H.W. Martin, assigned to the
Electrical Spectacle & Eyeglass Mfg Co.
Mohawk, New York

The device is an attachment to the bridge of ordinary spectacles, consisting of a zinc strip and a copper strip which clip together on the bridge.

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