PART I 



CHAPTER 1 

 INTRODUCTION TO OCEANOGRAPHIC OBSERVATIONS 



1-1 OCEANOGRAPHY, A DEFINITION.— 



Oceanography may be defined as the science 

 of the sea employing the principles of physics, 

 chemistry, meteorology, biology, and geology. 

 It originally included the world below the 

 surface of the sea. Today, however, it has 

 been extended to include those phenomena 

 which occur at the sea-air interface. As the 

 fund of knowledge expanded, it rapidly be- 

 came apparent that oceanography is made up 

 of several specialized sciences such as 

 marine biology, marine geology, chemical 

 oceanography, and physical (or dynamical) 

 oceanography. 



1-2 EARLY EXPLORATION.^The treat- 

 ment of oceanography from the geophysical 

 viewpoint is recent. Scientific work in oceanog- 

 raphy has been in progress but little more than 

 a century, however it is evident that there was 

 lively interest throughout ancient times. The 

 Phoenicians, Greeks, Romans, Arabs, and the 

 nations taking part in world exploration from 

 the time of Henry the Navigator laid the foun- 

 dation for modern oceanography. The list of 

 those ancients who showed sufficient interest to 

 speculate about the ocean includes such famous 

 names as Herodotus, Aristotle, Eratosthenes, 

 Strabo, Pliny, and Seneca. 



Aristotle, "who lived from 384 to 322 B. C, 

 studied the physical properties of the sea as 

 far as possible without the aid of instruments. 

 He thought that the water was warmer and 

 saltier at the surface than at the bottom. He 

 believed that evaporation due to the sun's 

 heat would eventually dry up the sea. His 

 opinions on oceanography are to be regarded as 

 mere speculation, but his observations and 

 study of marine animals were of distinct scien- 

 tific value. 



In about A. D. 53 Pliny in his gossipy "Natu- 

 ral History" presented Aristotle's investiga- 

 tions modified by much subsequent superstition 

 and tradition. He placed the greatest depth of 

 the ocean at 1,500 fathoms, a figure far too low. 

 He conjectured that the sea was salt because of 

 evaporation due to the sun's heat. 



H. O. 607 



Very few of the theories advanced in this 

 early period of the study of the sea have any 

 present merit, but the necessary geographical 

 knowledge was obtained, without which the 

 present structure could not have been erected. 



The real beginning of oceanography, with 

 recognition of its great scope, was the British 

 Challenger Expedition of 1873-76. Among the 

 important expeditions since that time may be 

 mentioned the German Meteor, of 1925-27, 

 and the American Carnegie, of 1927-29. Since 

 the end of World War II there have been 

 around-the-world expeditions carried out by 

 the Swedish Albatross and the Danish Galathea. 



The expense of extended voyages covering 

 large areas was no doubt the chief reason why 

 systematic examination of even the surface 

 of the sea was not seriously considered until 

 the middle of the nineteenth century. The 

 voyages of the Lightning, Porcupine, and 

 Challenger brought on a rapid development of 

 instruments which permitted investigations of 

 the greatest depths. These techniques for 

 sounding the contours of the sea floor; the 

 gathering of samples of the bottom; of sampling 

 the organisms and measuring the physical 

 characteristics of the sea, advanced so that by 

 the last decade of the nineteenth century 

 scientists were in a position to use the knowl- 

 edge gathered effectively. The results stimu- 

 lated many subsequent expeditions in various 

 parts of the world. 



From that time forward, with ev^ry new 

 expedition and with improvements in technical 

 methods and instruments came a flood of new 

 facts pouring in so rapidly that more was 

 learned about the sea and its inhabitants dur- 

 ing the last quarter of the 19th century than 

 had been learned before. 



Toward the end of the last century there 

 came a pause in the regional descriptive era of 

 oceanography. New schools arose centering 

 their attention on mathematical analyses of the 

 acquired data of the physical properties. 

 This conscious alteration of the viewpoint from 

 the descriptive to the analytic is one of the 



