The Wurzburg Antenna shown in March 1953, Image No. DTM18150.

The bulk of Carnegie's instrument photograph collection are images of the equipment obtained, designed, or modified by the Department of Terrestrial Magnetism.  Particularly well represented are objects associated with geomagnetic, ionospheric, and high-voltage research, all of which were key areas of work for the department during the time period that the images were taken, roughly 1906 to 1956.  The department continued to expand its research foci into areas such as radio astronomy and isotope geochemistry.