I really like how this thread has grown and everything is nicely executed.
Great Britain, SSK "A" Class Submarines (1902-1904).
Amongst the earliest of the home grown British subs. I ran into the class while surfing on-line,..stumbled on a maritime archeological firm's efforts to document the remains of "A-7" which sank with all hands.
The drawing documents the two basic conning tower designs. What's not evident are the incremental interior design changes in engines, etc. These early boats were expirimental to say the least.