Mrs. Rabbitt's third volume covers the years 1904 to 1939, from the beginning of the conservation movement under Theodore Roosevelt to the beginning of World War II. From a national perspective, these were years of great development and change in the use of energy, trouble in the coal industry, and a great expansion in the oil industry. They were also years in which the public perceived for the first time that the Nation's mineral resources are not infinite, and the mineral industry realized its dependence on international trade. In these years, water became an increasingly valuable commodity, and the need for a national mapping program became abundantly evident. These were also the years when the Federal Government for the most part practiced stringent economy in funding science, but State and municipal agencies increasingly sought the services of the Survey's topographic and water specialists to aid in the solution of local problems. The balance maintained between fundamental and practical research during the first 25 years was more than once upset during the next 25 years, but the successful struggle to maintain a significant level of research laid the groundwork for the tremendous expansion in the Survey in the subsequent years.
