February 24, 1880 Patent J.A. Thompsons Instantaneous Counterfeit Detector for United States gold and silver coins. Newman-Mallis IV-3-6. Bent plate rocker style detector. Nickel plated Brass. Extremely Fine.A simple design that allows for testing of five different gold denominations and four different silver ones. Marked at the upper left, J.A. THOMPSON’S /INSTANTANEOUS / COUNTERFEIT DETECTOR. / PAT.APL.3.77 / IMPROVED JAN.5.78. Each slot is marked numerically for the denomination intended, the top being marked GOLD and the bottom, SILVER. At the left end of the bottom side (when the makers mark is at the upper left), is the patent date FEB.24.80. According to the Newman-Mallis reference, this was the third of Thompson’s counterfeit detector patents. Light silver finish with some wear on the edges where the underlying brass shows through. Apparently rare, as we do not recall having seen this variety before. Photocopies of the original box labels are included with this lot.
