Scientific Medical & Mechanical Antiques
A bimonthly publication for the collector, dealer, and researcher
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.