Fig. 5. A medieval portrayal of the legendary descent of Alexander the Great. He is the 

 first man who is reputed to have dived deep into the ocean merely to look at the fish. 

 Several versions of the story declare that he saw a monster which took three days to swim 

 past his glass cage! Note the lamps, which may be called the prototypes of the bathy- 

 sphere searchlight. From a French manuscript of the thirteenth century. 



(Courtesy of the Bibliotheque de Bourgogne, Brussels; and of the New York Public Library) 



