Geodetic Survey.—A geodetic survey is the application of Geodesy, that higher science of surveying in which the form and magnitude of the earth must be considered. It has for its object the exact location of points and lines with reference to the true shape of the earth, the variations of terrestrial gravity, etc. In the United States coast and geodetic survey, attention has also been given to changes in temperature, magnetic currents, etc. The first magnetic observatory with self-recording instruments was established at Key West, Fla., in 1860 and maintained until 1866. From 1876 to 1880 observations were taken at Madison, Wis., and in 1882 an observatory was established at Los Angeles, where it was kept in operation for about seven years. The instruments used at Key West and Madison were the Brooke magnetograph, and at Los Angeles the Adie magnetograph was used.

In 1899 Congress made a more liberal appropriation for a systematic magnetic survey, and observations were made at various points during the next five years. In June, 1901, an Eschenhagen magnetograph was mounted at Baldwin, Kan. It was placed in a building not specially erected for such purposes and great difficulty was experienced in keeping it properly adjusted. W. C. Bauer was in charge of the station until June, 1902, when he was succeeded by W. F. Wallis, who served until July, 1903. L. B. Smith then occupied the position until the following October, when Mr. Bauer returned and conducted the observations until April, 1904. L. B. Smith then had charge of the station until it was discontinued the following December. During this entire period the government observers were assisted by students of Baker University.

The results at the various observatories were transmitted to the headquarters of the coast and geodetic survey at Washington, D. C., and turned over to the division of terrestrial magnetism. In 1909 the results of the observations at Baldwin were published in a bulletin of the department of commerce and labor, edited by Daniel T. Hazard. The bulletin shows the daily and monthly range in temperature; the diurnal variation of declination; the daily and hourly range of declination, the diurnal variation and hourly values of intensity, and many other facts of interest to scientists, but most of which are beyond the understanding of the layman.