EXPLORING THE FLOOR 27 



evidence many authorities in the following centuries 

 declared the ocean to be "immeasurably deep." * 



Toward the end of the eighteenth century serious 

 attempts were made to investigate the deeper layers 

 of the ocean. During the expedition of Captain Phipps 

 (later Lord Mulgrave) to the Arctic in 1773 a record 

 sounding of over 4,000 feet was taken. It brought up a 

 sample of blue mud. Dependable soundings in great 

 depths were first made by Sir James Clark Ross during 

 the British Antarctic Expedition of 1839-43, when the 

 first abyssal sounding on record was taken in the south- 

 east Atlantic, showing a depth of nearly 15,000 feet or 

 2,425 fathoms, a figure which in the light of modern 

 research is considered quite probable. The great stim- 

 ulus to early deep-ocean research came, however, 

 from biologists. In the early 1840's Edward Forbes, the 

 leading marine biologist of his day, repeated Aristotle's 

 study of the marine organisms in the i^gean Sea, made 

 over 20 centuries earlier.'' From the fact that the deeper 

 he went the more rapidly the marine organisms de- 

 creased, Forbes inferred that there is a lower limit, a 

 "zero line," of organic hfe at about 1,800 feet, which he 

 believed due to lack of light and a prevailing high 

 pressure. This would mean that only a relatively thin 

 surface layer of ocean is populated, the deeper and 



* Rational views regarding the deep sea and its investigation 

 were first expounded by Conte Luigi Ferdinando Marsigli 

 (1735), 2 who objected to the idea of immeasurability of the 

 ocean and indicated methods of measurement. 



