Colt New Police model, a double-action, six-shot revolver produced between 1896 and 1907. Your serial number, 38583, indicates a likely manufacturing date in 1907, which was the final year of production before it was replaced by the improved Police Positive model. It is chambered in .32 New Police (which is dimensionally identical to .32 S&W Long) and features the characteristic swing-out cylinder and hand ejector that became standard for modern revolvers.