The annexed engravings are views of an instrument for detecting counterfeit coins, invented by H. G. Robinson, of Schuylkill Haven, Penn. Figure 1 is a longitudinal vertical section of the instrument taken through the centre. Fig. 2 is a detached view of the clamps, and flg. 3 is a longitudinal vertical section of the case,the clamps being withdrawn and applied to the case for the purpose of weighing the coin in the receptacle at one end of the case. Similar letters refer to like parts. A represents a cylindrical case or tube, having at one end a receptacle or gauge box, B. This box is also cylindrical, and fits within the case, A, and is secured there (by a screw; a, attached to a partition, b, which serew passes into a nut, c, in the bottom of the box, B. The receptacle or gauge box, B, maybe sufficiently large or deep to contain several pieces of coin. At the upper or outer end of the box there is a recess ,d, cut through and around just one half the circumference of the box ; this recess will consequently admit a coin to be passed through it as large as the box will contain. The width of the recess must equal the width of a genuine coin of such a size as the box is capable of holding. The remaining portion of the case, A, incloses a pair of clamps, C ; these clamps are attached at one end to a rod, D, by a pivot, e. The opposite ends of the clamps are provided With points,,/,/". The rod, D, has a screw thread cut upon it, at one end, which screw-thread passes into the centre of the screw, a, as the rod, D, is turned; and the rod and clamps are thereby secured within the case, A. In order to detect counterfeit coin, the gauge box, B, is withdrawn from the case, A. If the coin will pass snug- ly through the recess, d, into the box, it must of course be of the same dimensions as a genuine coin, and if a counterfeit it will be lighter. The clamps, C, are then withdrawn from the case, A, and the small points,;/7 J\ are inserted in fulcrum holes, g g, one on each side of the case. These fulcrum holes are placed at certain points in the case, so that when a genuine coin is in the box, B, and the box adjusted within the case, A, the case will exactly balance or be in equilibrium, when it is suspended at the fulcrum holes, (see fig. 3), the coin being represented by h. If a counterfeit coin be of the same weight as a genuine one it will necessarily be larger, and will not pass through the recess into the box, B, weighing, in this case, would be unnecessary- If the receptacle or gauge box, B, contains several coins, they must be all removed when a coin is to be tested by weighing, and the coin to be tested should be moistened to cause it to adhere to the end of the box, as seen in fig. 3. as a change of position of the coin would cause great inaccuracy in weight. Bank notes may be wound around the rod, D, and clamps, C, within the case, and the implement will thus form a convenient receptacle for both com and bank notes, equally as portable as the ordinary wallet or pocket-book. Measures have- been taken to secure a patent, and more iniormatioji may be obtained by letter addressed to the inventor.
This article was originally published with the title "Counterfeit Coin Detector" in Scientific American 8, 18, 144 (January 1853)