I was doing some research on an old Smith & Wesson I had seen but couldn't identify.This gun was on display at the Springfield Arsenal in Springfield, Mass, just down the road from Smith & Wesson. Came up with some interesting data, for all you students.
The gun was a .44 rimfire, single action, spur trigger, SOLID FRAME revolver. According to an article by Roy Jinks (Smith & Wesson Handguns '96) this was Smith's first attempt at building a large caliber revolver to attract Government contracts. The gun looked similar to the No. 1 1/2 tip-up, but was larger and solid framed. In the meantime, S&W had procured rights to patents to make the top-break No. 3 revolver. The first No. 3 was in .44 Henry rimfire and submitted to Army Ordnance for consideration. The Army returned it, asking it be made "central fire." According to Jinks, this was done without changing the cartridge and chamber dimensions. Thus, the .44 S&W American cartridge is dimensionally identical to the .44 Henry rimfire.
In the back of my mind, I remember reading of late production Winchester 1866 Yellowboys being made in .44 S&W center fire, and have heard some Winchester collectors allude to a .44 Henry Centerfire, which probably would be one and the same.
The Army, incidentally, bought 2000 of these revolvers for tests, but deemed them unsuitable for military use.