The United States Counterfeit Detector, and Teachers' Guide
Heath, Laban (1871)
Book Summary
Newman variety HH-2. The "budget" version of the counterfeit detector, aimed at family use within the home. The ubiquity of the 19th century counterfeit detectors (and market for same) conveys a sense of the scope of the problem - getting stuck with spurious currency was a more common experience than today.