Gulf Gravity Pendulum

In the 1920s, as American companies began using scientific tools for petroleum prospecting, the Marland Oil Co. established a geophysical research laboratory; hired a PhD physicist named Englehardt August Eckhardt and an electrical engineer named Ralph D. Wyckoff; and purchased two sets of Mendenhall pendulum apparatus. Since this apparatus "afforded a precision of measurement which was just barely sufficient" for prospecting purposes, Eckhardt and Wyckoff developed a more precise instrument. The key element of their design was a minimum period pendulum made of fused quartz, a material that was physically stable and that minimized temperature corrections. General Electric supplied the quartz, the largest pieces of this material it had yet made.
The Gulf Research & Development Corp. hired Eckhardt and Wyckoff in 1928, and asked them to design new pendulum equipment based on their past experience. By 1935, Gulf had 10 pendulum instruments in the field. The pendulums were ground and polished by J. W. Fecker from pieces of fused quartz produced by General Electric. The bearings for the knife-edges were made of Pyrex. The optical work for the instrument was done by Bausch & Lomb.
For geological purposes, the Gulf pendulum instruments were replaced by gravimeters in 1936. For geodetic purposes, however, they remained useful and important for much longer. Indeed, some examples were used during the International Geophysical Year, 1957-1958. The Gulf Research & Development Corp. donated this example to the Smithsonian in 1962.
Ref: Malcolm W. Gay, "Relative Gravity Measurements Using Precision Pendulum Equipment," Geophysics 5 (1940): 176-191.
"Pendulum and Gravimeter Measurements of the Earth's Gravity," Transactions of the American Geophysical Union 39 (1958): 1205-1211.
Currently not on view
Object Name
gravity pendulum (Gulf)
date made
Gulf Research & Development Corp.
overall: 20 in x 23 in x 13 1/2 in; 50.8 cm x 58.42 cm x 34.29 cm
place made
United States: Pennsylvania, Harmarville
ID Number
catalog number
accession number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Natural Resources
Data Source
National Museum of American History, Kenneth E. Behring Center


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