This is Harvey Maranville's first counterfeit U.S. coin detector with a patent date of January 10, 1857; he patented a second detector in 1860 and a third in 1878. At this time, I have not found the patent # (a search of the patent office should identify this information). This is a rocker style detector with a small bottom stand. You place the coin in the hoder on the left, and move the slider on the right to the position which identifes the denomination in question. Overall, a very creatively designed and fairly unique counterfeit coin detector from the 19th century.