Yale's Bicentric was just a means to make truely LARGE master key systems. You could on one keyway have all the masters and the other just change keys. and they both would be different keyways. So as you can see you could have say 4000 master keys and about 500,000 change keys for each change key keyway. So if you had a campus you could issue out keys to each room on campus and still have a master that had no direct connection to the master, unlike master key systems of today.

It's downfall was that you couldn't do it outside of large locks so once the modern levers came into use the use of this type of cylinder also fell.