HYDROGRAPHICAL INVESTIGATIONS 201 



immense amount of such research was carried 

 out : all the seas of the globe were traversed, and 

 an enormous number of observations were made. 

 The methods of the Challenger were to make 

 a series of soundings, at the same time securing 

 a sample of the deposit forming the floor of the 

 ocean. In this way the depths and contours of the 

 ocean beds were determined, and a very full know- 

 ledge was obtained of the nature of the bottom. 1 

 The temperature, specific gravity, and salinity of 

 the sea-water, both at the surface and at a number 

 of depths down to the bottom, were also observed, 

 and samples of water from various depths were 

 taken in many parts of the oceans for chemical 

 analysis. The movements of oceanic waters form- 

 ing the great currents were also determined by 

 direct observations, by floats, etc., and by a study 

 of the temperatures and specific gravities. Baro- 

 metric and other data were also obtained. The 

 result of the Challenger s work was to give us a 

 very full knowledge of the sea from the point 

 of view of that department of physics called 

 " oceanography." Little or no attention was, 

 however, directed to the study of the practical 

 problems of the sea-fishing industry, though, no 

 doubt, the observations of the Challenger were 

 of immense assistance in further hydrographical 

 fisheries research. 



1 Our knowledge of these matters has been largely supplemented 

 by improved methods elaborated by the deep-sea cable companies. 



