Some have been successful, some sadly disastrous.

The river is always a new problem in its details, though the general conditions remain the same.
Major Powell was a man of prompt decision, with a cool, comprehensive, far-reaching mind.

He was genial, kind, never despondent, always resolute, resourceful, masterful, determined to overcome every obstacle.
To him alone belongs the credit for solving the problem of the great canyons, and to Professor Thompson that for conducting most successfully the geographic side of the work under difficulties that can hardly be appreciated in these days when survey work is an accepted item of government expenditure and Congress treats it with an open hand.
I am indebted to Mr.Robert Brewster Stanton, who completed the Brown Expedition triumphantly, for valuable information and photographs and for many interesting conversations comparing his experiences with ours; to the Geological Survey for maps and for the privilege of using photographs from negatives in the possession of the Survey; and to Mr.
John K.Hillers for making most of the prints used in illustrating this book.

My thanks are due to Brigadier-General Mackenzie, U.S.Engineers, for copies of rare early maps of the region embraced in our operations, now nearly impossible to obtain.
In 1902 when I informed Major Powell that I was preparing my history of the Colorado River, he said he hoped that I would put on record the second trip and the men who were members of that expedition, which I accordingly did.

He never ceased to take a lively interest in my affairs, and the year before he wrote me: "I always delight in your successes and your prosperity, and I ever cherish the memory of those days when we were on the great river together." Professor Thompson only a month before he died sent me a letter in which he said: "You are heir to all the Colorado material and I am getting what I have together." These sentiments cause me to feel like an authorised and rightful historian of the expedition with which I was so intimately connected, and I sincerely hope that I have performed my task in a way that would meet the approval of my old leader and his colleague, as well as of my other comrades.