The third specimen is a decided advance on the preceding guns. This arm (fig. 3, Plate which was found in the Armoury at the Tower, is furnished with a pyrites wheel lock, and one priming-pan is common to all the six chambers of the revolving breech; this pan is fitted with a sliding cover, and is so arranged that the serrated edge of a vertical wheel may project into it, amongst the loose powder in the pan; to this wheel a rapid rotary motion is given, by means of a trigger spring acting upon a link lever, attached to the arbor of the wheel, the teeth of which, striking upon the pyrites, create the sparks which ignite the priming powder. The fire is then communicated laterally to a train of powder about 21} inches long, before it reaches the charge In the breech, and which train of powder and priming require to be renewed each time before the charge' m the adjoining chambers can be exploded. A stop-pin is made to enter the orifices' In the wheel, to stay its action until the proper time, and on pulling the trigger the firing Is effected. In this instance, also, the breech is rotated by hand, and the barrel and breech are brought into contact by a nut working upon the threaded end of the breech arbor. By the employment of one priming-pan for all the chambers, and from the apparent necessity for closing the rear end of the breech with a cap, so as to leave but one small Opening for the passage of the fire, from the priming-pan to the breech, the liability of the several chambers to be simultaneously fired was greatly increased; for the cap, which covers the rear end of the breech, prevents the escape of the fire laterally, and forms, in fact, a channel for guiding the deﬂected fire to the touch-holes of all the charges. This gun has no stock in front of the breech; but unlike the previous specimens, the barrel is cut away on each side, so as to allow the balls to escape in case Of premature Oxplosion. A pistol of nearly identical construction (fig. 4, Plate 1) is in the collection at the Rotunda, at Woolwich.