62 



as in the South Sea, that, when we change both 

 latitude and longitude at the same time, the 

 waters often do not change one degree of tem- 

 perature, in an extent of several thousand square 

 leagues ; and that in the space comprised be- 

 tween the twenty-seventh degree north and 

 the twenty-seventh south, this temperature of 

 the seas is almost entirely independant of the 

 variations of the atmosphere # . A very long 

 calm, a momentary change in the duration of 

 the currents, a tempest mingling the inferior 

 strata of the water with the upper, may for 

 some time produce a difference of two or even 

 three degrees ; but as soon as these accidental 

 causes cease to act, the temperature of the ocean 

 resumes it's former stability. I shall have 

 occasion to return to this phenomenon, one of 

 the most invariable that nature offers. 



I have constructed a chart of the temperature 

 of the seas, as well from my own observations, 

 made from the forty-fourth degree of north to 

 the twelfth degree of south latitude, and from 

 the forty-third to the hundred and fifth of west 



* To show what little influence the air has on the tempera- 

 ture of the immense basin of the seas, I have added, in the 

 journals, the indication of the heat of the atmosphere to that 

 of the heat of the ocean. The latter may be changed by 

 very remote causes, such as the more or less rapid melting of 

 the polar ice, or winds blowing in other latitudes, and produc- 

 ing currents. 



