Gilles Mariette, an arms manufacturer in Cheratte, Belgium, pateneted the 'cluster revolver (pepperbox) with double action' in 1837. This percussion-era weapon is distinguished by its mutliple rotating barrel design. Its barrels, instead 
of being bored from a single block, were screwed separately onto individual chambers milled into a rotating breechblock.
Each barrel had four rectangular slots at 90 degree intervals round the muzzle to facilitate its removal with a special key, and each barrel was also numbered, along with each chamber. The cluster of barrels was screwed to a spindle on the standing breech, access to which was gained by way of the space left in the center of the cluster of barrels. Various pepperbox designs had as few as four barrels to as many as eighteen barrels, as shown here.
In most designs the percussion cap nipples were in the same axis as the barrels. This reduced the chances of a misfire and made the arm neat and compact, although in models with larger numbers of barrels some cap nipples had to be offset from their barrels. Pressure on the ring-trigger caused the barrels to rotate, bringing each in turn into line, and also drew back and released the internal hammer, which struck the cap nipple on the lowest barrel.
There are partitions between the nipples, and in addition, a further shield rose as the hammer fell to completely cover the cap being fired. Re-capping was achieved by pressing the trigger sufficiently to allow the barrels to be manually rotated; a small slot was provided in the right-hand side of the frame, allowing the caps to be slid into place.