59 



ment never exceeded 3*7°. Sometimes it did 

 not even rise higher than one or two degrees ; 

 but the heat in the body of the vessel, and the 

 humid wind which blows by fits, render experi- 

 ments of this kind very difficult. I have repeat- 

 ed them with more success on the ridge of the 

 Cordilleras, and in the plains, by hourly com- 

 paring, in perfectly calm weather, the power of 

 the Sun with it's height, the blue color of the 

 sky, and the hygrometrical state of the air. 

 We shall examine in another place, whether the 

 variable differences observed between the ther- 

 mometer in the Sun, and the thermometer in 

 the shade, depend only on the greater or less 

 extinction of light in it's passage through the 

 atmosphere. 



TEMPERATURE OF THE SEA. 



In my observations on the temperature of 

 the waters of the sea, I had in view four objects 

 very distinct from each other ; the decrement 

 of heat in the successive strata of the air ; the 

 indication of shoals by the thermometer ; the 

 temperature of the seas at their surface ; and, 

 finally, the temperature of the currents, which, 

 flowing from the equator * to the poles, and 

 from the poles to the equator, form warm or cold 

 streams -f- amid the motionless waters of the 



* The Gulf-stream, 

 f The current of Chili, which, as I have elsewhere proved, 

 draws the waters of the high latitudes toward the equator. 



2 A 



