327 



perature of the hottest month at Cairo is only 

 29^°; it is at Madras 31*8° ; and at Abushar, 

 in the Persian Gulf, where regular observations 

 have been made, it is 34° ; but the mean tem- 

 perature of the whole year is lower at Madras, 

 and at Abushar, than at Calabozo. Although 

 a part of the Llanos is traversed, like the 

 fertile steppes of Siberia, ^by little rivers, and 

 banks extremely arid are surrounded by land 

 that is inundated in the season of rains, the air 

 is in general very dry. The hygrometer of 

 Deluc* kept during the day at 34°, and by 

 night at 36°. 



In proportion as the Sun rose toward the 

 zenith, and the earth and the strata of superin- 

 cumbent air took different temperatures, the 

 phenomenon of mirage displayed itself with it's 

 numerous modifications. This phenomenon is 

 so common under every zone, that I mention it 

 only because we stopped to measure with some 

 precision the breadth of the aerial interstice 

 between the horizon and the suspended object. 

 There was constantly suspension, without inver- 

 sion. The little currents of air, that swept the 

 surface of the soil, had so variable a temperature^ 

 that in a drove of wild oxen, one part appeared with 

 the legs raised above the surface of the ground, 

 while the other rested on it. The aerial inter- 



* See abov e, ch. Xt f p.' 88 of this \ oL 



