cylinder to line each chamber up with the side-mounted loading gate. Smith & Wesson followed seven years later with the Hand Ejector, Model 1896 in .32 S&W Long caliber, followed by the very similar, yet improved, Model 1899 (later known as the Model 10), which introduced the new .38 Special cartridge. The Model 10 went on to become the best selling handgun of the 20th century, at 6,000,000 units, and the .38 Special is still the most popular chambering for revolvers in the world. These new guns were an improvement over the Colt 1889 design since they incorporated a combined center-pin and ejector rod to lock the cylinder in position. The 1889 did not use a center pin and the cylinder was prone to move out of alignment. Revolvers have remained popular to the present day in many areas, although in the military and law enforcement, they have largely been supplanted by magazine-fed semi-automatic pistols such as the Beretta M9 and the SIG Sauer M17, especially in circumstances where reload time and higher cartridge capacity are deemed important. Patents Elisha Collier of Boston, Massachusetts, patented a flintlock revolver in Britain in 1818, and significant numbers were being produced in London by 1822. The origination of this invention is in doubt, as similar designs were patented in the same year by Artemus Wheeler in the United States, and by Cornelius Coolidge in France. Samuel Colt submitted a British patent for his revolver in 1835 and an American patent (number 138) on February 25, 1836, for a Revolving gun, and made the first production model on March 5 of that year. Another revolver patent was issued to Samuel Colt on August 29, 1839. The February 25, 1836, patent was then reissued as entitled Revolving gun on October 24, 1848. This was followed by on September 3, 1850, for a Revolver, and by on September 10, 1850, for a Revolver. was issued to Roger C. Field for an economical device for minimizing the flash gap of a revolver between the barrel and the cylinder. In 1855, Rollin White patented the bored-through cylinder entitled Improvement in revolving fire-arms . In 1856, Horace Smith & Daniel Wesson formed a partnership (S&W), developed and manufactured a revolver chambered for a self-contained metallic cartridge. Design A revolver works by having several firing chambers arranged in a circle in a cylindrical block that are brought into alignment with