126 THE OCEAN RIVER 



vation was marked by two extensive compilations. The first 

 was based on a considerable amount of material collected by 

 the British Admiralty ofEce during the first part of the nine- 

 teenth century and carefully summarized by Major James 

 Rennell, whose book and charts, published posthumously in 

 1832, included courses of currents, wind directions, soundings, 

 and water temperatures. Rennell concluded that the breadth 

 of the Gulf Stream varies more than twofold within a period 

 of little more than two months, and that the variations are 

 independent of seasons. He also found that the south side of 

 the Stream is more unsteady than the north side, and that 

 warm water may be present in the eddies as well as in the main 

 current — thus it became known that temperature is not 

 always a true indicator of its boundary. He also confirmed the 

 presence of cold water masses within the body of warm water, 

 but the true nature of this strange phenomenon was still 

 unsuspected. 



The second compilation was made by Lieutenant Matthew 

 Fontaine Maury of the U. S. Navy. While superintendent of 

 the U. S. Naval Observatory he took advantage of an unusual 

 opportunity for studying ocean currents, and in carrying out 

 the tedious work of digesting a great amount of data he laid 

 the foundations for the modern system of ocean charts. He 

 began by collecting all the log books of vessels between 1 840 

 and 1850. The summaries were then published in the form of 

 wind and current charts and as sailing directions of the greatest 

 practical and commercial value. The scope of his contribution 

 to navigation and oceanography became international when 

 he called a maritime conference at Brussels in 1853 in order to 

 devise a uniform system of observations at sea. As a result, the 

 co-operation of a large number of nations was insured, and 

 data were collected from which more elaborate and detailed 

 information could be prepared. Much of the summarized 



