This revolver, designed by Fordyce Beals (how cool of a name is that?), was developed while Colt’s patent on using the hammer to index the cylinder was still in effect. To avoid that patent, this Beals design uses the trigger to rotate and index the cylinder, with the hammer being cocked separately. The gun was manufactured by Eli Whitney, who ran an industrial factory specializing in working with independent inventors who did not have the capital or resources to do their own manufacturing.
This model of revolver is commonly known as a walking beam or walking lever type, after the mechanism of the trigger moving the cylinder. This was a mechanism commonly used in other application to convert linear motion to rotational motion.
Beals would go on to work with the Remington company on his later pocket pistol design, and would have a major part in designing Remington’s 1858 Army revolver.