Looking to starboard in the control room. The dive plane station is visible at left. Each set of hydroplanes, forward and aft, has its own electric control box, which is surrounded by a manual control wheel. Electric control was used by default, but the electric hydroplane motor could be disengaged and the manual wheel used if desired. Beside the hydroplane station is the ballast tank blowing manifold. In the foreground is the shaft of the radio direction finder loop, and next to it at its top is a gray sound-powered telephone. To the right is the ladder leading to the conning tower. The green cylinders contain pure oxygen. There was equipment in the control room and both torpedo rooms to keep the flow correct for a specified number of men in those rooms. The oxygen could be metered either into the room or into the ventilation ducting. (Caption courtesy of Matt Hamacher)