NATURAL 
remote from terrestrial bodies, to 
receive a communication of heat 
from them; they att only upon 
such as are adjacent. Hence you 
will easily perceive, that the rays 
of the sun cannot produce any ef. 
_ fe& in regions of the air very much 
elevated above the surface of the 
earth ; and that the same degree of 
cold must’ always, and universally, 
prevail in such regions, as the sun 
has no influence there, and as the 
heat of terrestrial bodies cannot be 
communicated so far. This is 
neatly the case on the summit of 
very high mountains, where it is 
always much colder than on_ plains 
and in valites*. 
. The city of Quito,’ in Pera, is 
almost under the equator, and were 
we to form our judgment from irs 
situation on the globe, we wou!d 
suppose it oppressed with intoler- 
able heat; the air, however, is 
abundantly temperzic, and differs 
very little from that of Paris. 
Quito is situated at a great height 
above the real surface of the earth. 
In going to it from the sea shore, 
you have to ascend for several days ; 
it is accordingly built in an eleva- 
tion equal to that of our highest 
mountains, though surrounded by 
others still much higher, called the 
Cordeliers. This last circumstance 
would afford a reason for thinking, 
HISTOR [391 
that the air there must be as hot as 
at the surface of the earth, as it is 
contiguous on all sides, to the epaque 
bodies, on which the rays of the 
sun fall, The obje€tion is solid; 
ai no solution can be given but 
this: that the air at Quito, being 
very elevated, mast be much more 
sudtile, and of less gravity than 
withus; and the barometer, which 
always stands considerably lower, 
incontestibly proves ir. 
Air of such a quality is not so 
susceptible of heat as common air, 
as if must contain Jess vapour and 
other particles which usualiy float 
in the atmosphere; and we know 
by experience, that air, very much 
loaded, is proportionably suscepti- 
ble of heat, { mast here subjcia 
another phenomenon, no_ less suz- 
prising : in ‘very deep pits, and 
lower still, at it were still possible 
to descend, the same degree of heat 
always, and univezsaily prevails, 
and nearly for the same reason. 
As the rays of the sun exert their 
influence only on the surface of the 
earth, and as the heat which they 
there excite communicates itself 
up and down, this effeét, at very 
great depths, is almost impercep- 
tible. Tle same thing holds re. 
specting considerable height, This 
elucidation will, I flatter myself, 
prove satisfactoryt. 
Account 
* There are clouds, however, above these mountains, and in almost as great a 
quantity as above the plains, which is demonstrated by the snows which cover the 
highest sammits. There are few naturalists who h ve not been surprised by 
clouds in their excursions upon-the mountains, ‘The heat that is felt when such 
clouds are formed, must be attributed almost entirely tu the transm’ssion of the water 
which found itself dissolved in the air, under the form of elastic fluid, to a liquid 
state. The heat of the solar rays, intercepted by the cloud, can produce no 
change in- he inferior temperature, as it would have been transmitted from the 
ground—F. E. 
+ The reason which professor Euler assigns for the cold that prevails in the 
higher regions of the atmosphere seems plausible, but will not stand an accurate 
examination, Light is much impaired in its passage through the atmosphere, 
Cc4 and 
