The included book "Colt Brevete Revolvers" by Marcot and Paxton pictures an almost identical revolver on p. 304, and these "Brooklyn Bridge" revolvers are described on p. 298-307. They are so-named due to the suspension bridge scene often rollmarked on the cylinder, which collectors have since dubbed the Brooklyn Bridge. The top of the barrel is marked "ADDRESS COL SAML NEW MODEL U.S. PATENTED" with the typical "crossed keys" at either end. The matching serial number "32" is on the left of the front and back strap, right of the rammer, and inside both grips. Belgian proofs are visible on the right of the frame and barrel and it is fitted with smooth hardwood grips.