R.L. Wilson wrote “First of the Sidehammers, with grooved cylinder surface, proved impractical.”
Rather interesting. If you look closely at the images you will note a sliding bar attached to the hammer. The bar indexes the cylinder, using the diagonal cuts on the cylinder, as the hammer is cocked. Notice the “creeping gear” loading lever.
The revolver is in the Elizabeth Hart Jarvis Colt Collection at the Wadsworth Atheneum Museum of Art in Hartford, Connecticut. (Photo: Wadsworth Atheneum Museum of Art)