Herbert Hoover was a Mining Engineer and author before becoming President of the United States of America during the great depression of the 1930s. This book is fully illustrated and comes with an index. In the Preface, Hoover describes the book in this way: "This volume is a condensation of a series of lectures delivered in part at Stanford and in part at Columbia Universities. It is intended neither for those wholly ignorant of mining, nor for those long experienced in the profession."