31(5 
METEOltOLOGICAI/ PHENOMENA. 
90° to 83°. The heat of the day was from 28° to 32°, which 
for this part of the torrid zone is very considerable. Some- 
times, in the midst of the night, the vapours disappeared in 
an instant; and at the moment when I had arranged nr 
instruments, clouds of brilliant whiteness collected at the 
zenith, and extended towards 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 could distinguish so perfectly the spots of the moon, that 
it might have been supposed its disk was before the clouds. 
The latter were at a prodigious height, disposed in bands, 
and . at equal distances, as from tho effect of electric re- 
pulsions: — these small masses of vapour, similar to those 
I saw above mv head on tho ridge of tho highest Andes, 
are, in several languages, designated by the name of sheep. 
When the reddish vapour spread lightly over the sky,' the 
great stars, which in general, at Cumana, scarcely scintillate 
below 20° or 25°, did not retain even at the zenith, their 
steady and planetary light. They scintillated at all alti- 
tudes, as after a heavy storm of rain* It was curious that 
the vapour did not affect the hygrometer at tho surface of 
tho earth. I remained a part of the night seated in a 
balcony, from which I had a view of a great part of the 
horizon. In every climate I feel a peculiar interest iu fixing 
my eyes, when the sky is serene, on some great constel- 
lation, and seeing groups of vesicular vapours appear and 
augment, as around a central nucleus, then, disappearing, 
form themselves anew. 
After the 28th of October, the reddish mist became 
thicker than it had previously been. The heat of the nights 
* I have not observed any direct relation between the scintillation of 
the stars and the dryness of that part of the atmosphere open to our 
researches. T have often seen at Cumana a great scintillation of the stars 
of Orion and Sagittarius, when Saussure’s hygrometer was at 85°. At 
othei times, these same stars, considerably elevated above the horizon, 
emitted a steady and planetary light, the hygrometer being at 90° or 93°. 
Probably it is not the quantity of vapour , but the manner in which it ir 
diffused, and more or less dissolved in the air, which determines the scin- 
tillation. The latter is invariably attended with a coloration of light. It 
is remarkable enough, that, in northern countries, at a time when the 
atmosphere appears perfectly dry, the scintillation is most decided in vert 
cold weather. 
