Found this picture of this historic pistol design. The intent is clear – a gun that lets you fire bullets quickly with minimal reloading bother. The flaw in the design should be equally as clear – the weight/balance would make aiming with this pistol really tricky.
This is the Jarre Double Action Harmonica Pistol and that “clever” chamber hoses nine pinfire 38 cartridges. The gun can fire double as well as single action. You can just about see the secondary trigger attached to the rear of the primary one in the picture.