Patented in 1885 by Romanian military officer Haralamb Dimancea, this revolver is actually a true hammerless design. Instead of simply shrouding a hammer inside the frame, Dimancea used a pair of rotating sprockets to cock and release a striker and act as hand and stop for the cylinder. The Gatling Arms Company of Birmingham England produced a run of 1,000 of the guns, which were used in Romanian military trials, and also tested by the French as a replacement for their 1873 revolver. Neither country ended up adopting the gun, though.
A .45 caliber 5-shot version was apparently made in small numbers, but the standard pattern (like this example) is a .38 caliber, 6-shot model. The barrel, crane, and cylinder pivot 90 degrees to the left to extract empty cases and reload. While Dimancea’s design was innovative, is really did not provide any benefit over a traditional revolver, and is considerably more complex to manufacture. It fires in double action only, with no mechanical way to manually cock the action for a “single action” shot.