APPENDIX. 



L THE GULF STREAM. 



As the results of the systematic investigation of the Gulf Stream 

 upon a plan laid out by Dr. A. D. Bache, and executed, under his 

 direction, by his most able assistants, have hardly yet been presented 

 in a popular form, a sketch of the whole may not be out of place 

 here. This investigation embraced not only surface-phenomena, 

 but the whole internal structure and movement of this wonderful 

 current. It is well known that the Gulf Stream has its origin in 

 the equatorial current which, starting from the Gulf of Guinea, 

 flows for a time in a westerly direction, till it approaches Cape St. 

 Roque. This great projection of the eastern coast of South Amer- 

 : ,ja interrupts its onward progress, and causes it to divide into two 

 branches, one of which follows the coast of Brazil, in a southerly- 

 direction, while the other continues its course to the northwest, 

 until it reaches the Caribbean Sea. After pouring into that basin, 

 the great stream turns to the east to enter the Atlantic again off 

 Cape Florida. The high temperature of the equatorial current is 

 owing to its origin in the tropical zone, its westward course being 

 determined by the rotation of the earth and by the trade-winds. 

 On issuing from the Gulf of Mexico the stream is encased between 

 the island of Cuba and the Bahamas on one side and the coast of 

 Florida on the other. Here it meets the Atlantic in a latitude where 

 the ocean-waters have no longer the high temperature of the tropics, 

 whereas the stream itself has acquired an increased warmth on 

 the shoals of the Gulf. This accounts for the great difference of 

 temperature between the waters of the stream and tiioso of the 



