GEOGKAPHY. 349 



far as navigable. In the circulation and exchange ot important hydro- 

 graphic information and the correction and publication of charts, the 

 United States Hydrographic Office has silently aud unostentatiously 

 contributed a very great deal to geographic knowledge. 



The Coast Survey, from an early period in its existence, has devoted 

 much time and expense to investigations of the currents and tempera- 

 ture of the Gulf Stream ; but the apphances for both sounding and 

 ascertaining temperatures were very imperfect. The invention and per- 

 fection of the wire sounding-machine and the deep-sea thermometers 

 have afforded opportunities for correcting former errors and discovering 

 new features in hydrographic science, so that the results of the last ten 

 year's work are of more importance as far as our knowledge of the deep 

 sea goes than all the work done before. During the last two years 

 Commander J. E. Bartlett in the U. S. Coast Survey Steamer Blake 

 has been engaged in an examination of the Gulf Stream not only after 

 its full development has been reached on the coast of the United States, 

 but where the currents manifest themselves at the entrances from the 

 Atlantic Ocean to the Caribbean Sea. 



From the very numerous soundings and temperatures taken during 

 Commander Bartlett's cruises, and previously by Commander Sigsbee, 

 in the Gulf of Mexico, the following deductions may be drawn, subject, 

 however, to modification in minor details : * 



The equatorial current of the North Atlantic is deflected northward 

 by the coast of South America, a portion of it passing along the shore 

 of the Spanish Main, between Grenada and Trinidad. A larger portion, 

 however, pours into the Caribbean Sea, between the Windward Islands, 

 and another part, proceeding westward, north of Hayti, enters the Carib- 

 bean Sea by the Windward Passage, still more continuing along the 

 north shore of Cuba to the Straits of Florida. The water, warmed by the 

 sun while passing over a series of shoals and banks, is several degrees 

 warmer at the Windward Passage than at the Windward Islands. 

 Proceeding westward, the current, entering the Gulf of Mexico from the 

 Caribbean Sea, does not make the cii:cuit of the Gulf, and has no nec- 

 essary connection with the currents of the Gulf of Mexico, but passes 

 to the northward and eastward, issuing from the Straits of Florida with 

 such addition as may come from between Cuba and the Bahama Bank. 



The temjjerature of the Gulf Stream, in the early part of its course, 

 rarely exceeds 83° in June and July, except under a very hot sun in 

 calm weather. By carefully measuriug the area of the cross-section of 

 the stream between Jupiter Inlet and the Little Bahama Bank, as well 

 as its velocity, it is shown that the delivery is very much less than the 

 amount called for by the volume of warm water extending over the At- 

 lantic Ocean from Cuba to Norway, and heretofore ascribed to the out- 



* For these deductions the compiler is indebted to an excellent article in the Nation, 

 October 5, 1882. 



