It was found that the results of the investigation of underground waters were of great interest to the public, and the rapid development of many areas in the West through the use of underground water for irrigation, the application of well waters to the irrigation of rice in the Southern States, and the ever-growing importance of deep well waters as sources of public water supplies have led in the last few years to a great increase in the work involved in their investigation. In order satisfactorily to meet the new demands and to develop, specialize, and systematize the work, the investigations relating to underground waters were segregated from the division of hydrography and grouped into a distinct organization known as the division of hydro-geology, or hydrology. This organization was made at the beginning of 1903, with two sections, western and eastern, the first including the so-called reclamation States and Territories and Texas, and the second embracing the States east of the Mississippi and those bordering that river on the west. Each of these sections was placed in charge of a geologist assigned from the division of geology and working under the general supervision of the chief hydrographer.

In the western section there are three assistant geologists, two field assistants engaged throughout the year, and five field assistants engaged for a portion of each season. Special investigations are being conducted by several other geologists, in most cases State geologists and professors of geology at the State universities. In the eastern section there are several assistant geologists and many temporary field assistants. Arrangements have been made for cooperation by a number of local geologists, and several members of the geologic branch are giving special attention to restricted areas.

The work of the division includes the gathering, filing, and publication of statistical information relating to the occurrence of water in artesian and other deep wells; the gathering and publication of data pertaining to springs; the investigation of the geologic occurrence, from both stratigraphic and structural standpoints, of underground waters and springs; a study of the laws governing the variations due to tidal, temperature, and barometric fluctuations; direct measurements of rate of underflow; detailed surveys of regions in which water problems are of great importance and urgency, and the publication of reports on irrigation, city water supplies, and other important uses of underground waters.

To serve as a basis in outlining plans for field work, it was found desirable to undertake a preliminary correspondence by means of printed requests for the addresses of drillers, well owners, spring owners, etc., and for information relating to town water supplies, wells, and springs. Requests for addresses are first sent to postmasters, and to the addresses thus obtained special blanks are sent. The same system is used in gathering information from scattered

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account of expense. The THE UNITED STATES GEOLOGICAL SURVEY.

information thus obtained has been found to be of great value and assistance in carrying out the work of the division. recorded on printed cards of three types, designed for information

points which it is impracticable to visit on

The data are

FIG. 4.-Map showing progress of work on underground waters in western half of United States in 1903-4.

relating to city or town water supplies, deep wells, and springs. The cards are so arranged that they can be submitted directly to the printer as copy for tabular reports. Plans have been made whereby bibliographies covering hydrography and hydrology, similar to those which have proved of so much value to geologists, will be prepared annually.