386 Barometric Anomalies about the Andes. 
that the form or shape of the Andes is repeated in the atmosphere. 
In other words, that there is in the region of the clouds, a ri 
or pile of atmosphere, answering to an air-cast mould of the Cordil- 
leras ; for at the eastern base of the Andes he found the pressure of 
the atmosphere, as measured by the temperature of boiling water, 
to be nearly as great as it is usually at the sea level—and after 
having descended the river for nearly a thousand miles below this 
place of great pressure, he found that, ear to the boiling 
point, he had ascended nearly 1,500 fee 
These mountains extend from three . five miles up into the 
atmosphere. The Trade Winds blow almost perpendicularly 
against them. Of course, these winds are obstructed by an ob- 
stacle, which extends as far up, or nearly as far up, as they them- 
vesdo; and, being thus obstructed in their course, would there 
not, consequently, bea banking up of air against the Andes, as 
there is of water against a rock or other impediment, over which 
the current of a rapid river has to force its way? In such cases, 
there is a ridge or pile of water above the obstruction, aud a de- 
pression or hollow in the water both above and below this ridge. 
Herndon’s observations on the boiling point of water, have sug- 
gested to me the idea of an air-cast mould of the Andes in the 
atmosphere ; in other words: that there is to windward—that 48, 
to the eastward of the Andes, where the trade winds first im- 
pinge—an accumulation or ridge of atmosphere, with a _— or 
depression on each side of i 
To illustrate this, I have had a diagram drawn, upon the su 
position that the average descent of the Amazon from Chasuta, at 
Ms iot ee thee le 
*% 
‘ 
aia ‘ee 
Horizontal scale 500 miles to an inch, Vertical scale 8000 feet to an inch. 
a, Tarma 9,441 te ait re 0 10,036 feet.—c, Junin 12,436 feet.—d, Ninacacca 
% tiajo'3 236 feet. Pry Fg oh 8,088 feet —g, Hnunuco 5 feet 
eatin Maria 1,923 for h tacenhe} feet —k, Chasute- 
bove Barra 
oe os 
. 
