rw, yes, that was the first time a diving bell was used to rescue submariners. I have a paperback book at the house about the whole incident and it also covers Swede Momsen, who was in charge of the rescue. Swede also was heavily involved with designing the rescue bell, the escape lung and mixed gas diving.

I should offer it up as a karma here I guess, for the history buffs like myself. It's not in the best of shape, but it is still readable. The name of it is "The Terrible Hours: The Greatest Submarine Rescue in History" by Peter Maas.