The same state of things is strikingly obvious upon continents wherever
the mountains are sufficiently elevated, even within the trade-wind
region. Thus, in South America, the Andean ranges are of great elevation,
and spurs and table-lands extend from them a considerable distance to the
eastward. There, the S. E. and N. E. trades of the Atlantic meet in very
considerable volumes, and not only is the equatorial belt much wider than
upon the Atlantic and Pacific, but the counter-trades are met upon the
elevated peaks and mountain-ranges, and showers and storms on their
eastern slopes and summits are frequent during the dry season--down even
to the extra-tropical belt. I have already said that it was probable that
the great elevation of the Andes diverted and turned south a portion of
the N. E. counter-trade which would otherwise pass over the western coast
of Peru.

The report of Lieutenant Herndon, which has come to my notice since that
was written, states facts which strongly corroborate that opinion. It
seems that the trades and counter-trades actually _bank up_, in their
passage to the westward, against those mountains, and the true elevation
of their eastern slopes can not be barometrically ascertained. (See report
of the Exploration of the Amazon, p. 261). Lieutenant Herndon says:

"I was surprised to find the temperature of boiling water at Egas to
be but 208 deg. 2', the same within 2' of a degree that it was at a point
one day's journey below Tingo Maria, which village is several hundred
miles above the last rapids of the Huallaga river; at Santa Cruz, two
days above the mouth of the Huallaga, it was 211 deg. 2'; at Nauta, three
hundred and five miles below this, it was 211 deg. 3'; at Pebas, one
hundred and seventy miles below Nauta, 211 deg. 1'. I was so much
surprised at these results that I had put the apparatus away,
thinking that its indications were valueless; but I was still more
surprised, upon making the experiment at Egas, to find that the
temperature of the boiling water had fallen 3 deg. below what it was at
Santa Cruz, thus giving to Egas an altitude of fifteen hundred feet
above that village, which is situated more than a thousand miles up
stream of it. I continued my observations from Egas downward, and
found a regular increase in the temperature of the boiling water
until our arrival at Para, where it was 211 deg.