6 



A JOURNEY IN BRAZIL. 



carried ai under our government. Mr. Agassiz gave a slight 

 sketch of this in opening his lecture. " It was Franklin 

 who first systematically observed these facts, though they 

 had been noticed long before by navigators. He recorded 

 the temperature of the water as he left the American con- 

 tinent for Europe, and found that it continued cold for 

 a certain distance, then rose suddenly, and after a given 

 time sank again to a lower temperature, though not so low 

 as before. With the comprehensive grasp of mind charac- 

 teristic of all his scientific results, he went at once beyond 

 his facts. He inferred that the warm current, keeping its 

 way so steadily through the broad Atlantic, and carrying 

 tropical productions to the northern shores of Europe, must 

 take its rise in tropical regions, must be heated by a tropical 

 sun.* This was his inference : to work it out, to ascertain 

 the origin and course of the Gulf Stream, has been, in a 

 great degree, the task of the United States Coast Survey, 

 under the direction of his descendant. Dr. Bache." f 



^ " This stream," he writes, " is probably generated by the great accumu- 

 lation of water on the eastern coast of America, between the tropics, by the 

 trade-winds which constantly blow there." These views, though vaguely 

 hinted at by old Spanish navigators, were first distinctly set forth by Frank- 

 lin, and, as is stated in a recent printed reoort of the Coast Survey Explo- 

 rations, " they receive confirmation from every discovery which the advance of 

 scientific research brings to aid in the solution of the great problem of oceanic 

 circulation." 



t No one can read the account of the explorations undertaken by the 

 Coast Survey in the Gulf Stream, and continued during a number of successive 

 years, and the instructions received by the officers thus employed from the 

 Superintendent, Dr. A. D. Bache, without feeling how comprehensive, keen, 

 and persevering was the intellect which has long presided over this department 

 of our public works. The result is a very thorough survey of the stream, es- 

 pecially along the coast of our own continent, with sections giving the temper- 

 ature to a great depth, the relations of the cold and warm streaks, the form of 

 the ocean bottom, as well as various other details respecting the direction and 



