ILLUSTRATIONS 
Page. 
View of Rio Colorado, from an island near the Mojave villages, looking north.Frontispiece. 
View of San Antonio Pass....... 25 
View of Aztec Pass_______ 35 
Diagrams representing abnormal oscillations of the barometric column— 
General map from Fort Smith to Rio del Norte, upon a scale of one inch to 15 miles. 
General map from Rio del Norte to the Pacific ocean, upon a scale of one inch to 15 miles. 
Profile of a route for the Pacific railroad, from Fort Smith to Martinez, near San Francisco. 
