222 



THREE CRUISES OF THE " BLAKE. 



within the ridges separating it from the Atlantic, the deepest 

 soundings, such as those off Bequia, 1,591 fathoms, and off Mar- 

 tinique, 1,224 fathoms, indicate a bottom temperature of 39^**. 

 From St. Thomas to Ham's Bluff (Santa Cruz), on the con- 

 trary, the temperature section seems to indicate that the deep 

 water there (2,376 fathoms, with a bottom temperature of 

 38i°) is connected by a deep channel extending between Som- 

 brero and Virgin Gorda with the cold Atlantic water. The 

 temperatures in the section across the passage between Domi- 



1 JOurft, Zi.l873. 



V3 m ea ^ n «% 



^ ^ * c] ^ S0 



i'l.daJkiable 



Fig-. 145. 



nica and Martinique (Fig. 145) show an extraordinary fall 

 between 50 and 150 fathoms, — from 71° to 53° ; then a much 

 colder layer between 150 and 300 fathoms, with a bottom tem- 

 perature of 424° at a depth of only 430 fathoms. The bottom 



Jlicrth, 2S JS79 



PtBardy 



Fig. 146. 



temperature in the northern part of the passage wa:s 41** at a 

 depth of 575 fathoms. 



In a section from Martinique to St. Lucia (Fig. 146), with a 

 somewhat larger area than that of the southern part of the pas- 

 bottom temperature of 39^°. The " Al- perature of 39^° at the greatest depth 

 batross " also ran a line across the east- recorded, — over 2,600 fathoms, 

 ern Caribbean, and found a bottom tem- 



