The difference of
the mean height of the Cordilleras (between 5 degrees north and 2
degrees south latitude) and the Swiss Alps, is consequently 200 toises
less than the difference of their loftiest summits; and in comparing
the passes of the Alps, we see that their average height is nearly the
same, although peak Nethou is 600 toises lower than Mont Blanc and
Mont Rosa. Between the Himalaya* (* The passes of the Himalaya that
lead from Chinese Tartary into Hindostan (Nitee-Ghaut, Bamsaru, etc.)
are from 2400 to 2700 toises high.) and the Andes, on the contrary,
(considering those chains in the limits which I have just indicated),
the difference between the mean height of the ridges and that of the
loftiest summits presents nearly the same proportions.
Taking an analogous view of the groups of mountains at the east of the
Andes, we find the average height of the coast-chain of Venezuela to
be 750 toises; of the Sierra Parime, 500 toises; of the Brazilian
group, 400 toises; whence it follows that the mountains of the eastern
region of South America between the tropics are, when compared to the
medium elevation of the Andes, in the relation of one to three.
The following is the result of some numerical statements, the
comparison of which affords more precise ideas on the structure of
mountains in general.* (* The Cols or passes indicate the minimum of
the height to which the ridge of the mountains lowers in a particular
country. Now, looking at the principal passes of the Alps of
Switzerland (Col Terret, 1191 toises, Mont Cenis, 1060 toises; Great
Saint Bernard, 1246 toises; Simplon, 1029 toises; and on the neck of
the Pyrenees, Benasque, 1231 toises; Pinede, 1291 toises; Gavarnic,
1197 toises; Cavarere, 1151 toises; it would be difficult to affirm
that the Pyrenees are lower than the average height of the Swiss
Alps.)
TABLE OF HEIGHTS OF VARIOUS RANGES.
COLUMN 1 : NAMES OF THE CHAINS OF MOUNTAINS.
COLUMN 2 : THE HIGHEST SUMMITS IN TOISES.
COLUMN 3 : MEAN HEIGHT OF THE RIDGE IN TOISES.
COLUMN 4 : PROPORTION OF THE MEAN HEIGHT OF THE RIDGES TO THAT A THE
HIGHEST SUMMITS.
Himalayas (between north latitude : 4026 : 2450 : 1 : 1.6.
30 degrees 18 minutes and 31 degrees
53 minutes, and longitude 75 degrees
23 minutes and 77 degrees 38 minutes)
Cordillera of the Andes (between : 3350 : 1850 : 1 : 1.8.
latitude 5 and 2 degrees south)
Alps of Switzerland : 2450 : 1150 : 1 : 2.1.
Pyrenees : 1787 : 1150 : 1 : 1.5.
Littoral Chain of Venezuela : 1350 : 750 : 1 : 1.8.
Group of the Mountains of the Parime : 1300 : 500 : 1 : 2.6.
