TEMPEEATURES. 229 



passage between Martinique and St. Lucia. They are actually 

 lower than the temperatures of the corresponding depths ob- 

 served in the passage between Martinique and Dominica. 



On the Caribbean side of Dominica the series of bottom tem- 

 peratures shows a marked increase from the surface to a depth 

 of over 800 fathoms, and we must go to nearly 1,000 fath- 

 oms before we find the deep-sea isothermal of 39.7°. At 600 

 fathoms there is a ternperature of over 40° ; at 542 fathoms, 

 of 42°. Comparing this with the temperatures outside of the 

 Windward Islands, we find them considerably lower at a depth 

 of 250 fathoms, and only slightly lower from that point to 600 

 fathoms. 



Off Guadeloupe on the western side, the bottom temperatures 

 between 62 fathoms and 300 fathoms are liioher than at corre- 

 sponding depths off Martinique, Dominica, and St. Lucia, and 

 the same is the case off the islands of St. Kitts, Nevis, Mont- 

 serrat, and the Saba Bank. This increase in temperature of the 

 upper strata extends to a depth of over 250 fathoms. The broad 

 bank which the above-named islands form upon the inner edge 

 of the Caribbean seems to raise to an abnormal degree the tem- 

 perature of the water which covers it, while the narrow bank of 

 which the Grenadines form the crest appears to act more as a 

 dividing ridge, cold water being brought nearer the surface on 

 the Atlantic side of these islands, as is the case with the cold 

 water on the dividing ridges in passages between adjoining- 

 islands. 



The same high temperature is continued in the line of bot- 

 tom soundings observed off the western extremity of Santa 

 Cruz, where at a depth of 625 fathoms we still find 41° ; at 

 450 fathoms, 42F ; at 314 fathoms, 48°; and at 248 fath- 

 oms, 54i°. These temperatures agree well with those found 

 outside, at similar depths, off Sombrero. That is, the strata 

 of water to the eastward of the northern Windward Islands 

 between 625 fathoms and 250 fathoms are much warmer than 

 the same belt to the south, while the belt on the lee side 

 between 250 and 100 fathoms is sliohtlv colder. In the line 

 of bottom temperatures between St. Thomas and Santa Cruz, 

 we find at 218 fathoms only 51°, a temperature which corre- 



