There are a lot of spellings here at Google, including
bathyskape. 'Guess it depends on the country of origin. Bathyscap
th shows up nowhere.
Here's a site with a very impressive progression of underwater bathys-
whatevers. (But not "our" bathys-
whatever).
http://www.shipsonstamps.org/Topics/html/tauch.htm
Trieste had a diving ball (bathysphere)
attached. (But Trieste itself is called a bathy
scaphe). It was most famously operated by Jean-Luc -- I mean --
Jacques Piccard.
I have a 5x7 B&W photograph of the Trieste being discussed dockside by a uniformed Navy captain (four-striper) and two engineers. It was bought at an Alton yard sale, and the Trieste photo was preserved behind the primary, now long-forgotten, photograph.