Ocean Magnetic Survey Expeditions
In the early decades of the 20th Century, teams of "magnetic observers" from the Department of Terrestrial Magnetism criss-crossed the globe from the polar regions to the tropics. Making delicate measurements of the direction and strength of the earth's magnetic field as part of a "World Magnetic Survey," DTM observers travelled by sailing ships and railroads, by camel trains and in oxcarts, on horseback and on foot.
J. P. Ault typified the "can do" spirit of the survey era. Joining DTM the year of its founding (1904), Ault proved himself an able observer and a gifted organizer of field research. He sailed on the research vessels Galilee and Carnegie and commanded the latter from 1914 to 1929, during which time he also headed the ocean survey section of the Department.
For more about the history of DTM's ocean survey expeditions, see Ocean Magnetic Survey Expeditions Web site.
Dots on the map below show locations at which magnetic measurements were made by DTM observers up to 1935. Ocean tracks show the cruises of the ships Carnegie, Galilee, and Maud. Click on the Carnegie flag pins to visit some of the places Captain Ault travelled on the World Magnetic Survey.