New York: A. L. Burt, (1913). Hardcover - From a publisher's ad: "The story deals with a little-known stretch of river, from the Gulf of California to the Grand Canyon. The plot is a strong one, and the clue sought is at last discovered by two venturesome lads who start out to have a Òlittle fun of their own on the side." As in all other volumes of this aeries, the authorÑperhaps the best-known writer of boysÕ books in the countryÑtells something of the history of the country the boys pass through." Glossy frontispiece of the Grand Canyon. 256 pp.

New York: Hurst and Company, (c 1910). Hardcover - The first book in this series described by the publisher as one which marks "a new era in boys' books - the wonders of modern science epoch." Features Frank and Harry Chester who, with their $10,000 prize airplane, rescue a chum from death, discover a lost treasure valley and more. Glossy frontispiece and 4 inserted plates on plain paper. The publishers claim that a million copies of this series have been sold. 336 pp plus 8 pp publisher's ads.