EFFECTS OF THE MIBAGE. 
103 
surface of the ocean. The illusion was augmented when 
the disk of the sun appearing on the horizon, repeated its 
image by the effects of refraction, and, soon losing its 
flattened form, ascended rapidly find straight towards the 
zenith. 
Sunrise in the plains is the coolest moment of the day ; 
hut this change of temperature does not make a very lively 
UUpression on the organs. We did not find the thermo- 
meter in general sink below 27‘5 ; while near Acapulco, at 
. exieo, and in places equally low, the temperature at noon 
is often 32°, and at sunrise only 17° or 18°. The level surface 
. the ground in the Llanos, which, during the day, is never 
pa the shade, absorbs so much heat that, notwithstanding 
the nocturnal radiation toward a sky without clouds, the 
e arth and air have not time to cool very sensibly from mid- 
Ul ght to sunrise. 
In proportion as the sun rose towards the zenith, and the 
®arth and the strata of superincumbent air took different 
eaperatures, the phenomenon of the mirage displayed 
tself in its numerous modifications. This phenomenon 
s so common in every zone, that I mention it only 
'■■cause we stopped to measure with some precision the 
I'eadth of the aerial distance between the horizon and the 
Suspended object. There was a constant suspension, with- 
°ut inversion. The little currents of air that swept the 
surface of the soil had so variable a temperature that, in a 
I ' ° of wild oxen, one part appeared with the legs raised 
puove the surface of the ground, while the other rested on 
The aerial distance was, according to the distance of 
Av e animal, from 3' to 4'. Where tufts of the moriehe palm 
ere found growing in long ranges, the extremities of these 
so 6 ] 611 r ° ws were sus P ei 'ded like the capes w hich were, for 
^ mug a time, the subject of my observations at Cumana. 
.well-informed person assured us, that he had seen, be- 
v Oalabozo and Uritucu, the image of an animal in- 
Uial ’ ^hout there being any direct image. Niebuhr 
th < l: , a s i triilar observation in Arabia. We several times 
tow- h" We . saw 011 *he horizon the figures of tumuli and 
abl 6r f’ w ^°h disappeared at intervals, -without our being 
. 1° discern the real shape of the objects. They were 
a ps hillocks, or small eminences, situated beyond the 
