In 1852 an employee of Colt's, Rollin White, came up with the idea of having the revolver cylinder bored through to accept metallic cartridges. He took this idea to Colt who flatly rejected it and ended up firing White within a few years. Colt historian RL Wilson has described this as the major blunder of Sam Colt's professional life. Rollin White left Colt's in December 1854 and registered a patent on April 3, 1855 in Hartford, Connecticut, as patent number 12,648: "Improvement in Repeating Fire-arms". On November 17, 1856 White signed an agreement with Smith & Wesson for the exclusive use of his patent. The contract stipulated that White would be paid 25 cents for every revolver, but that it was up to him to defend his patent against infringement as opposed to Smith & Wesson.