f 



314 



eating' greater humidity, often went back from 

 90° to 83°. The heat of the day was from 28° to 

 32°, which for this part of the torrid zone is 

 very considerable. Sometimes in the midst of 

 the night the vapours disappeared in an instant ; 

 and at the moment when I had arranged my 

 instruments, clouds of a brilliant whiteness were 

 formed at the zenith, and extended toward the 

 horizon. On the 18th of October, these clouds 

 were so remarkably transparent, that they did 

 not hide stars even of the fourth magnitude. 

 I distinguished so perfectly the spots of the 

 moon, that it might have been thought that 

 it's disk was placed before the clouds. They 

 were at a prodigious height, disposed in bands, 

 and at equal distances, as from the effect of 

 electric repulsions. These are the same small 

 masses of vapour, which I saw above my head 

 on the ridge of the highest Andes, and which 

 in several languages bear the name of sheep. 

 When the reddish vapour was spread lightly 

 over the sky, the great stars, which in general 

 at Cum ana scarcely twinkle below 20° or 25°, do 

 not retain even at the zenith their steady and 

 planetary light. They twinkled at all altitudes, 

 as after a heavy storm of rain*. I was 



heat, the mean moisture of the atmosphere is from 78° 

 to 80°. 



* I have not observed any direct relation between the 

 twinkling of the stars, and the dryness of that part of the 



