>So . . . imagine you are a bank clerk in the 1870s, and your bosses tell you to keep on the lookout for counterfeit bills. What do you do? Nowadays, you can go to the Secret Service’s website, which has all sorts of advice: http://www.ustreas.gov/usss/money_detect.shtml. But it’s 1870! No computers! Well, you keep your handy-dandy Heath’s Infallible Counterfeit Detector, at Sight on hand as you sit at your teller window. According to the title-page, this is “the only infallible method of detecting counterfeit, spurious, and altered bank notes, and applicable to all banks in the United States and Canadas, as now in circulation, or that may be issued.”
Under “general directions,” Laban Heath (what a name!) says: In receiving bank-bills, first look at the general appearance of the bill, casting your eye across the bill, and if anything is wrong, it will probably catch your eye. Then examine the various parts more perfectly, examining the Geometrical Lathe work, and if necessary, compare it with plate I in this work [shown here is plate I]. (etc.). Very cool.