Page:Popular Science Monthly Volume 46.djvu/497

Rh attention was given to the consideration and solution of certain broad geologic problems presented by the wide domain of the United States. These problems embraced those of the geologic growth and development of a great continent, many of which had to be solved before the areal geographic mapping could be carried forward intelligently and with due consideration for scientific accuracy and economy. With the completion of topographic sheets, areal geology was gradually taken up, and in 1894 more than three fourths of the available geologic force was employed in areal work.

The scope of the work of the Geological Survey has thus come to include the preparation of a topographic base map of the entire United States; the study and mapping of the areal geology upon this base; the examination of the geologic structure and mineral resources of the national domain; the gathering of the statistics of mineral production; the study of the artesian and surface water supply of the United States; and, indirectly, the mineral and agricultural classification of the public lands under survey.

There is one fact that should be borne in mind when considering the scope of the work, and that is that the Geological Survey is a bureau of research. Its work is to a large extent the discovery of unknown facts and principles, and the scientific co-ordination of these and all known facts and inductions, within the scope of its work, in such a form that they shall subserve the use of both the Government and the people; the latter to include not only the farmer, prospector, miner, owner of lands, investor, and mining and civil engineer, but also the most highly trained students, teachers, and specialists.

—Captain George M. Wheeler said of topographic surveys: "The topographic is the indispensable, all-important survey, being general and not special in its character, which underlies every other, including also the graphic basis of the economic and scientific examinations of the country. . . . This has been the main or principal general survey in all civilized countries, and all other so-called surveys (as geodetic, trigonometric, etc.) are but accessories or addenda thereto. . . . The results of such a survey become the mother source whence all other physical examinations may draw their graphic sustenance."

A recent European writer (1892) on the general topographic maps of the present time says that all European states have undertaken uniform and continuous topographic surveys of their