250 



banks of the Temi. I attribute this difference 

 to the proximity of the savannahs of the Lower 

 Guainia, which permits the free access of the 

 breeze, and which also by their radiation cause 

 a stronger ascendant current than lands covered 

 with forests. 



The temperature of Javita* is cooler than that 

 of Maypures, but considerably hotter than that 

 of the Guainia or Rio Negro. The centigrade 

 thermometer kept up in the day to twenty-six 

 or twenty-seven degrees ; and in the night to 

 twenty-one degrees. The diurnal heat north of 

 the cataracts, and particularly, north of the 

 mouth of the Met a, was generally twenty-eight 

 or thirty degrees, and the nocturnal heat twenty- 

 five or twenty-six degrees. This diminution of 

 heat on the banks of the Atabapo, the Tuamini, 

 arid the Rio Negro, is no doubt owing to the 

 long absence of the Sun, a sky constantly cloudy, 

 and the evaporation of a humid soil. I do not 

 speak of the refrigerant influence of the forests^ 

 as furnishing in their innumerable leaves so 

 many thin substances, that grow cool by ra- 



* The 1st of May, at 19 h in the morning, therm, of Rea 

 mur, 17 7° 5 hygr. of whalebone, 6*1° j cloudy : at noon, th. 

 2V9° ; hygr. 48° j sky serene: at 4 h 30', th. 198°; hygr. 

 55-5°: at7 h , th. 20-2° 5 hygr. 60°: at I0 h , th. 19° j hygr. 

 62° 5 cloudy: at ll h , th. 18-2"; hygr. 6f>°. The 3d of May, 

 at 20\ th. 19° 5 hygr. 63° ; cloudy : at 0 h , th. 21*5° ; hygr. 

 49° ; clear: at 3 h , 15', th. 22° j hygr. 46' 5° : at 8»>, th. 

 20-2° ; hygr. 01° j cloudy. 



