Holweck-Lejay Gravity Pendulum

Description (Brief)
Along with gravimeters and torsion balances, pendulums can be used to measure gravitational force. The period oscillation of the pendulum can be used to measure gravitational acceleration, and in turn used in prospecting for natural resources. Different types of underground resources have different densities, increasing or decreasing gravitational attraction that can be detected by pendulums.
Fernand Holweck and Pierre Lejay, developed an elastic inverse pendulum in 1930, describing it to the Académie des Sciences as a portable instrument for the rapid measurement of gravity. A new model of 1932 was said to be ten time more precise than the original. A third model, unveiled later that year, was about two hundred times as sensitive to gravity changes as the ordinary free swinging pendulums. Holweck applied for French and German patents for this pendulum in 1933; a U.S. patent (#2,097,156) was assigned to the Shell Development Company in San Francisco. The Holweck-Lejay apparatus was used for large-scale government gravity surveys, particularly in France and China. Robert M. Iverson obtained this example from an oil company, and donated it to the Smithsonian in 1967.
Fernand Holweck (1890-1941) was a physicist who served for many years as Director of the Curie Laboratory of the Radium Institute in Paris. He was tortured and killed by the Gestapo. The Holweck Medal, instituted by the Societé Française de Physique and the British Institute of Physics, serves as a memorial to him.
Pierre Lejay (1898-1958) was director of the Jesuit astronomical observatory in China from 1930 to 1939, and made gravity surveys throughout China and the East Indies. At the time of his death he was director of the International Gravity Bureau, vice-president of the International Council of Scientific Unions, and chairman of the French national committee for the International Geophysical Year.
Ref: Fernand Holweck and Pierre Lejay, “Un instrument transportable pour la mesure rapide de la gravité, Comptes Rendus de l’Académie des Sciences 190 (1930): 1387-1388.
William Bowie, "Recent Developments in Gravity Apparatus," Science 77 (1933): 308-310.
A. J. Haskinson, A Test on the New Holweck-LeJay Gravity Apparatus, Journal of the Washington Academy of Sciences 26 (1936): 481-482.
L. L. Nettleton, Geophysical Prospecting for Oil (New York, 1940), pp. 30-31.
Pierre Lejay, Dévelopments Modernes de la Gravimétrie (Paris, 1947), pp. 26-32.
Lewis Pyenson, “Habits of Mind: Geophysics at Shanghai and Algiers, 1920-1940,” Historical Studies in the Physical and Biological Sciences 21 (1990): 161-196, esp.181-183.
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Work and Industry: Agriculture
Measuring & Mapping
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National Museum of American History


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