49 



study the laws of these phenomena, we must 

 exhibit them in groups, and not separately, as 

 they were successively observed. We are under 

 great obligations to navigators, who have accu- 

 mulated an immense number of facts ; but must 

 regret, that hitherto naturalists have made so 

 little use of their journals, which, when examin- 

 ed anew, may yield unexpected results. I shall 

 insert at the end of this chapter the experiments, 

 which I made on the temperature of the atmos- 

 phere and the ocean, with the hygrometrical 

 state of the air, the intensity of the blue color of 

 the sky, and the magnetic phenomena. 



TEMPERATURE OF THE AIR. 



In the vast basin of the Northern Atlantic 

 Ocean, between the coasts of Europe, Africa, 

 and the New Continent, the temperature of the 

 atmosphere offered m a very slow increment, 

 as we passed from the 43d to the 10th degree of 

 latitude. From Corunna to the Canary islands, 

 the centigrade thermometer, observed at noon 

 and in the shade, ascended gradually from ten 

 to eighteen degrees* ; from Santa Cruz in Te- 

 nerifte to Cumana, the same instrument rose 

 from eighteen to twenty-five degrees-}". In the 



* From the 6th to the 19th of June. See the particular 

 observations in the journal at the end of this chapter, 

 t From the 25th of June to the loth of July. 



