Photo No. 27. This Photograph shows one of the two Diving Bells just submerged, and the second Bell with its roof above water. Two of the Boats from which the Helmet Divers work are also to be seen. Each Bell measures 12 ft. 9 in. by 10 ft. by 6 ft. 6 in. high and weighs about 26 tons.
Submarine Appliances And Their Uses - 1911