The enquirer. [volume] (Richmond, Va.) 1804-1815, 1810-10-26
(coNrINuEp.)


teres,ing discussion We shall however, conten,
ourselves at present with offering few short re-
marks. So
& The mean temperature of any place depends on
two distinct conditions, its distance from the e.
quator, and its elevation above the The
warmth that WHITES our globe is all derived from
The rays OF the sun, which, being absorbed the
surface of the ground, and partly in the lower
strata Of the atmosphere, constitute the general
mass ofheat. But, in consequence ofthe obliqui-
~ ofthe earth's axis, combined with the effect
ofits rotundity, the proportion OF light which
falls in the various ATTITUDES is most widely diff
ferent The solar action is hence shared out
with such excessive inequality, that, if left to its
unmitgated influence, the several climates on
the surface ofthe globe would be divided by i'm.
passsble zones Our atmosphere. the great ve-
hicle of Impressions, performs that essential Of
fee; and, maintaining, by means of a complex
system of winds, slow yet continual intercourse
between the equator and the poles, transports the
heat of the sou;h to the frozen regions of the
north, and carries back the polar cold to fan the
xultry face of the tropicks; thus blending the
different effects, and attemperiDE the general
distribution of warmth a fluid of greater mo-
biiity or conducting power would still further
sluce the inequality of climates Had the atmos.
phere consisted ofhydrogen gas, the difference Of
temperature between the equator and the poles
wc;,ld have been three times less than what OBJ
tsins in the actual constitution of our globe -
From these principles, the law of temperature,
rs dependent on latitude, may be determined, "a
ereeing with the formula discovered by the cele-
brated Mayer of Gottingen, which, with slight
Gcation, corresponds with the most precise
observations. We should expect the mean tenn
perature ofyera Cruz to be 7SI degrees Hum
boldt, from register kept there for several years
states it at 7So but the heat of Callso the port
of Lima, which ought to be $50 is, apparently
on very slight grounds, noted SO low as So"
This difference, which exceeds, altogether, the
4 Aa. ib.ac
xhe effect ofa remarkable cold current that hows
along the western coast of America, from the
strait of Magellan to cape PARMA, and had, OPP
posite to Lima, only the temperature of 61'-
This singular current seems to be an exact
counterpart to the famous gulph stream, which,
on the other side of the continent, after having
swept the bay of Mexico, shoots towards the
northeast, till it loses itself in the Atlantick.
But the mean temperature IT any place is ma
serially affected by its elevation. rapid inter
change is necessarily maintained between the
higher and lower strata of the atmosphere. The
heat principally received at the surface. becomes
thus almost uniformly dlffused through the verti-
cal columns of air. When awarm portion of the
Auid rises from below, an equal portion must de
scend and this perpendicular communication,
being confined to space eight thousand times
smaller than the range OF the horizontal currents
which connect the equator with the poles. may
be considered producing Its full effect, and e:.
Publishing a perfect equilibrium. The same abso-
iute quantity of heat, therefore, exists at every
height of the atmosphere. the capacity of air
were net afiectedb by its density, uniform tenn
perature would, in consequence, prevail through
The whole vertical column. But since the pow
or of containing heat increases as the density of
the fluid is diminished, the temperature of the
higher regions of the atmosphere suffers cor
responding reduction The temperature which
obtains a, any elevation, is, therefore, inversely
proportional to the capacity for heat belonging to
air of such density. From this principle, gui-
ded by experiment, and further adjusted by OBJ
servation, derive a very simple formula for
expressing the dimmuton of temperature in the
vertical ascent. The graduation is not uniform, as
many have supposed, but decreases faster in the
upper regions OF the atmosphere This infer
ence is confirmed, by close inspection OF the
best and most extensive observations Under the
equator, tie decrement OF heat, IN mounting up
wards may be calculated, near the surface, at
S24 feet for each degree OF Fshrenheits scale
at 2e7 feet, when the height is 10 600 feet and at
21S feet, for an elevation off 600 feet NJ Hum
boldt reckoning the mean decrement at 344 feet,
considers IL as uniform to the height OF & 700 feet
and afterwards reduced TO three hflhs Of that
quantity beyond the elevation of 10000 feet -
This statement is quite anomalous but ii is con
nected with another strange opinion which he
has advanced, in supposing that, above the height
of three miles in the atmosphere, the same pre-
else degree of cold prevails, in the whole extent,
from the equator to the poles. The mean tenn
Derature of the city OF QUITO, at the neIgbt OF
9, $50 feet above the sea, may be computed at $50
and that of Mexico, which has an elevation of
r,475 feet at $50. Humboldt makes the former
20 be $50 !, and the latter 62s j both of them
obviously too great. The temperature of Mex-
co might indeed, be some what raised above the
standard, from the circumstance of its lying IN
the midsi of such vast tract of high country,
where the sun heat is directly absorbed, and the
communication between The upper and the under
strata OF tie atmosphere is necessarily rendered
cirCuitors.
But, when the observations of our ingenious
traveller become more precise, they cease to be
discordant with theory. In the torrid zone, the
limit Of perpetual congeIation is very distinctly
marked not varying more than 100 yards under
the equator, or 500 at the tropick of Cancer
This boundary according TO Humboldt, has an
lcyation of 700 leet the equator, and Is, 900
feet IN the latitude Of DO /, results which per
fectly agree with the formula. We may remark,
by the way, that the comparatively very narrow
MARGIN of The snow within the tropicks, causes
the nlaiestic Andes to want those glaciers, or icy
belts, which, IN Europe, bestow so much beauty
and grandeur or the Alpine scenery.
The settlers in New Spain distinguished the
cultivated part Of the country into three zones
l. The tieyras eaHeHtes or warm grounds, which,
never rising 900 feet above the sea, ave heat
OF about SO, and yield abundanlly, sugar, iDdi
20, cotton and plsntalns or bananas. 2. The IL
eryas fs1n6ladas, or temperate grounds, which, ~
ire- on tie decilvlty of the great ridge, at an al
titude from TO 5, 900 feet, enjoy mild, yernsl
Temperature Of 6so TO 100, that seldom varies IL
de grees through tie whole year. 3. The Heyrds
4 LII an ale linn ~