.41 RF. 2.5" tapered round barrel with top flat. SN: 4810. Silvered barrel, gilt brass frame, walnut stock with checkered bird's head grip. Single shot, single action cartridge derringer with sliding barrel, German silver blade front sight and no rear sight. Left side of barrel marked in a single line: WILLIAMSON'S PAT. OCT. 2, 1866 NEW YORK. Serial number under barrel and only visible when barrel is slid forward. Barrel engraved with floral scroll motifs at breech and muzzle and a large arrow on the top flat. Gilt brass furniture engraved en suite. While serial numbers approaching 20,000 are known, Flayderman's estimates production at closer to 10,000. The pistols were produced by Moore's Patent Firearms Company and then National Firearms Company circa 1866-1870.