the privilege of a military escort whenever I deemed one desirable,
and numerous letters of introduction to prominent persons in Northern
Mexico who were in a position to further my plans--I hurried back to
the United States to organise the undertaking. My plan was to enter,
at some convenient point in the State of Sonora, Mexico, that great
and mysterious mountain range called the Sierra Madre, cross it to
the famous ruins of Casas Grandes in the State of Chihuahua, and then
to explore the range southward as extensively as my means would permit.

The western Sierra Madre may be considered a continuation of the
Rocky Mountains and stretches through the greater part of Mexico into
Central and South America as a link of the Cordilleras, which form a
practically uninterrupted chain from Bering Strait to Cape Horn. The
section occupying Northwestern Mexico is called Sierra Madre del
Norte, and offers a wide field for scientific exploration. To this
day it has never been surveyed.

The northernmost portion of the Sierra Madre del Norte has from time
immemorial been under the dominion of the wild Apache tribes whose hand
was against every man, and every man against them. Not until General
Crook, in 1883, reduced these dangerous nomads to submission did
it become possible to make scientific investigations there; indeed,
small bands of the "Men of the Woods" were still left, and my party
had to be strong enough to cope with any difficulty from them.

Inasmuch as my expedition was the first to take advantage of the
comparative security prevailing in that district, I thought that
I could best further the aims of Science by associating with me a
staff of scientists and students. Professor W. Libbey, of Princeton,
N. J., took part as the physical geographer, bringing with him his