Before the development of the semi-automatic self-loading pistol, many ingenious attempts were made to solve the problem of the physical bulk of revolvers. The weapon shown here was such an attempt. It is a Belgian copy of a design by August Schuler of Suhl, Germany.
The basic lock mechanism was that of a normal double-action revolver, where the hammer acted on a firing pin in the frame. The front end of the frame though, consisted of a pair of parallel side-plates, between which fitted a set of four vertically stacked barrels. The four barrels were formed onto a solid vertical breech block and were aligned to chambers in the block that would hold four cartridges. These chambers were first loaded and then the barrel/block assembly was pressed down like a clip between the plates, where it was held in place by a small spring-loaded stud. The top round was fired first. Then pressure on the trigger raised the block of barrels so that the second cartridge was in line with the firing pin, ready for the next shot. After each shot, the trigger would raise the barrel/block so that the next cartridge would line up with the firing pin.
The three lower barrels had small holes drilled on their upper sides to connect each to the barrel immediately above; so, when the second and subsequent barrels were fired, enough gas passed upwards to blow out the empty case in the barrel above. The comb of the hammer was shaped in such a way as to deflect these ejected cases away from the direction of the firer's face. The final spent cartridge had to be manually removed.