GENERAL INTRODUCTION 9 



involving as it does the many branches of knowledge that 

 pertain to a study of the life and conditions of the environ- 

 ment in the oceans and seas. The study of the ocean 

 currents, the tides, the temperatures, and the saltness and 

 other chemical properties, is approached through pure 

 physics and chemistry. The charting of the ocean margins 

 and the mapping of the rehef of the ocean beds are matters 

 for physical geographers. Intimately bound up with the 

 great ocean currents and the tides are meteorological and 

 astronomical phenomena. The above studies constitute 

 hydrography, although this term is more usually apphed 

 to the survey and charting of those features only which have 

 a direct bearing upon navigation. There remains the study 

 of the life in the sea, marine biology, which involves zoology, 

 botany, bacteriology, and includes the study of animal and 

 plant development, the study of the abundance of life, and 

 many other problems; to these must be added the application 

 to the fishing industry of all knowledge of life and conditions 

 of life in the sea, fishery research. This composite whole 

 makes up the science of oceanography, which can be summed 

 up as the study of the world beneath the surface of the sea. 

 It is evident, therefore, that up to 1522 when Magellan 

 sailed into the Pacific ocean the true science of ocean- 

 ography had not begun ; all these exploratory voj'-ages had 

 but touched the margin of the geographical side. It is 

 true that Magellan made a sounding in the Pacific ocean, 

 but somewhat naively he argued that because he could not 

 touch bottom he had reached the deepest part of the ocean. 

 Soundings are recorded also in ancient times, but as yet there 

 was no systematic attempt to map in relief the ocean bed ; 

 in fact it is doubtful whether, owing to the backward state 

 of other sciences, it would then have been possible. It is 

 only within the last few years that it has been made rapid 

 and simple by the introduction of echo sounding. 



