"Is not the 41 Colt a rim fire?"
No.
There are actually two .41 rimfire cartridges, the .41 Short, which was chambered in the Remington Double Deuce derringer, the National Arms single shot (later purchased by Colt and sold under their name) and the Colt Cloverleaf.
I believe that the .41 Long rimfire was a Colt innovation.
The two centerfire cartridges that more or less matched these were the .41 Short Colt and the .41 Long Colt. These both were developed and first brought to market by Colt.
Invariably, though, if someone asks about a .41 Colt cartridge, they mean one of the centerfires, and almost always it's the .41 Long Colt.