228 THREE CRUISES OF THE " BLAKE." 



Barbados. The temperature is 45° at a depth of 225 fathoms, 

 at 347 fathoms off Barbados ; it is 40° at 350 fathoms, while 

 the same temperature is found at a depth of 713 fathoms off 

 Barbados. That is, the layer of water below 150 fathoms be- 

 comes gradually warmer as we go north from Pernambuco, the 

 isothermal of 40° being at 350 fathoms off Pernambuco, while 

 it is at 700 fathoms off Barbados and Sombrero. The isother- 

 mal of 50° is at 150 fathoms off Pernambuco, at 225 fathoms 

 off Barbados, and at 350 fathoms off Sombrero. 



A line of soundings southwest by south from Saline Point off 

 Grenada shows the water to be as a whole colder than at simi- 

 lar depths off Barbados. Off Grenada at 400 fathoms we find 

 41°, at Barbados 44° ; at 350 fathoms, the temperature is only 

 about 1° colder off Grenada; at 300 fathoms, it is again 2° 

 colder ; at 150 fathoms, about 3° ; and at 100 fathoms, only 1°. 

 A series of bottom temperatures on the lee side of Grenada 

 shows the water for depths between 100 and 400 fathoms to be 

 considerably warmer than that of the corresponding depths 

 standing in free communication with the Atlantic. At a depth 

 of 92 fathoms, the water on the lee side is 32° warmer than that 

 of the same depth on the windward side. The same difference 

 exists at 300 fathoms, and at 400 fathoms the temperature on 

 the lee side is still 1° warmer. 



The bottom temperatures on the lee side of St. Vincent show 

 a similar difference. The bottom temperatures off St. Lucia on 

 the lee side are shghtly colder than those off St. Vincent and 

 Grenada, but they are warmer than the temperatures at iden- 

 tical depths in the passage between St. Lucia and St. Vincent, 

 and from St. Lucia to Martinique. The lower temperature is 

 probably due to the deeper passages admitting cold water on 

 each side of St. Lucia, as compared \vith the depths at which 

 water pours into the Caribbean south of Grenada, or across the 

 bank of the Grenadines and through the shallower passage be- 

 tween St. Vincent and Bequia. We must, however, call atten- 

 tion to the remarkably cold temperature occurring between 127 

 and 171 fathoms on the lee side of the Grenadines. 



On the lee side of Martinique the bottom temperatures are 

 still lower, — fully as low as those of the same depths in the 



