[3] LISTS OF THE DREDGING STATIONS. 875 



very large area only from 2,000 to 2,050 fathoms, as is shown by the 

 east and west section across the Gulf, which is also given. 



The three sections, from the Cultivator Shoal, or George's Bank, 

 from Hatteras, and from Charleston, illustrate the general fact of the 

 very gentle slope of the sea bottom along our eastern coast until the 

 depth of about 100 fathoms is reached and of its very abrupt descent 

 beyond that line, whilst they show the very different distances from 

 shore at which this line is found. 



The two sections showing the temperatures in the Mediterranean and the 

 Caribbean Sea illustrate the factthatina deep basin closed by a barrier 

 of shallower soundings no change of temperature occurs from a depth 

 corresponding with that of the barrier to the very greatest depths. In 

 the Mediterranean the temperature found at a depth of about 120 

 fathoms, that of the Straits of Gibraltar, is about 574° Fahr. and does 

 not vary to a depth of more than 2,000 fathoms, whilst in the Caribbean 

 and Gulf of Mexico the deepest channel communicating with the ocean 

 appears to be about 800 fathoms, corresponding to a temperature of 

 39J° Fahr., and below this depth this temperature is invariably found 

 down to 2,000 fathoms and more. The temperatures marked upon the 

 section of the Gulf of Mexico illustrate this fact more fully. 



The other temperature sections show the very rapid diminution of 

 temperature from the surface and the very low temperatures reached 

 iu great depths. 



As, after the preparation of the chart of the Carribbean Sea, the sec- 

 tions illustrating depths and temperatures were found, when reduced, 

 to be too small for convenient use, enlarged copies of them are given as 

 separate plates, numbered 5a, 5b, and 5c. 



The tables of serial temperatures, taken by the Speedwell, Fish 

 Hawk, and Albatross, afford the means of studying these changes of 

 temperature in greater detail. These tables, like those of positions, 

 have been scattered through numerous volumes, and, as requiring the 

 aid of charts for their intelligent use, it has been considered best to 

 bring them together in connection with these. 



The hydrographic stations of the Albatross having been published 

 for the most part by the Hydrographic Office as well as in the Fish 

 Commission reports, and requiring only very rarely to be referred to by 

 their serial numbers, the lists of them have not been reprinted. 



