Submarine identification help needed...

[lambda*sqrt(u*x)]

...in the 1916 movie "20,000 Leagues Under The Sea", which submarine did the team use for the maritime scenes?

http://bedroommedia.com/watch.php?vid=637∂=5622

I couldn't figure out if it was a mock-up or, perhaps, some Holland class?

EDIT: By the way, after the 9th minute the movie shows scenes which depict the modus operandi of watch crews on early submarines not featuring conning towers or sails.