51 



sea is from twenty-six to twenty-seven degrees. 

 We must exclude from this statement the ob- 

 servations made during a dead calm, because 

 the body of the vessel is then extraordinarily 

 heated, and it is almost impossible to make a 

 just estimation of the temperature of the atmos- 

 phere. When we look into the journals of so 

 many celebrated navigators, we are surprised to 

 see, that never, in either hemisphere, have they 

 observed the thermometer under the torrid zone, 

 in the open sea, above 34° (27*2° R). In thou- 

 sands of observations made at the time of the 

 passage of the Sun across the meridian, we 

 scarcely find a few days when the heat has risen 

 to thirty-one or thirty-two degrees (24*8° or 

 25*6° R.) ; while on the continents of Africa and 

 Asia, under the same parallels, the temperature 

 often exceeds thirty-five or thirty-six degrees. 

 In general, between ten degrees of north and 

 ten of south latitude, the mean heat of the at- 

 mosphere that rests on the ocean appears to me, 

 in the low regions, from one to two degrees 

 lower than the mean temperature of the air that 

 surrounds the land situate between the two tro- 

 pics. It is useless in this place to observe how 

 much this circumstance modifies the climate of 

 the whole Globe, on account of the unequal dis- 

 tribution of the continents at the north and south 

 of the equator, as well as to the east and west of 

 the meridian of Teneriffe. 



