The following is a summary of a lecture given to the Institute, in the Science Museum's lecture theatre, on 5 May 1954. Dr. G. E. R. Deacon, F.R.S., Director of the National Institute of Oceanography, was in the chair. The lecture was illustrated by slides and a film.

Alexander the Great was probably the first deep-sea diver. He is supposed to have had a glass boat made and to have spent some ninety days under the water observing strange and rare animals which, it may be conjectured, were no more than mythological. Since that time a number of attempts at producing diving spheres were made, but apparently without success until in 1832 a Spaniard made one of wood, which he went down in, and, unfortunately, never came up. In 1892 a steel sphere was made by an Italian, Balzamello, who reached a depth of 165 metres. The next developments were those of the Americans Beebe and Barton, much later, in 1930–34. They dived to 908 metres in a sphere attached to its parent ship by cable. Later on Barton by himself achieved 1380 metres.