Convert between gals and other major units of acceleration.

A unit of acceleration due to gravity used in geodesy and geophysics, = 1 centimeter per sec per second. It is named for Galileo Galilei.



It is a little surprising to find in Dr. Shaw's paper (December 16, 1913), “... He (Mr. Whipple) points out that we have no special name for the unit of acceleration”. In NATURE of June 25, 1914, Mr. Whipple proposed the name “leo”. So long ago as 1909 Wiechert used the term “gal” in the report for the Göttingen earthquake station for that unit, being the first syllable of Galileo, whence Mr. Whipple derives his “leo”. Others, as well as myself, have used “gal”, or rather “milligal”, in analyses of earthquakes. A milligal is approximately a millionth of g. Dyne is the unit of force, gal the unit of acceleration.

Otto Klotz.
Unit of Acceleration.
Nature, vol. 93, issue 2337, page 611 (1914).
doi: 10.1038/093611d0.

Klotz was a prominent early seismologist, affiliated with the Dominion Observatory in Ottawa.


In the standard form of report the maximum intensity or acceleration, designated by the symbol a, or max. a, is given in the conventional unit, the milligal. The milligal is a measure of acceleration, such that 1 milligal = 1/100 mm. per sec. per sec. = 10 μ per sec. per sec.

Weekly Bulletin of the Hawaiian Volcano Observatory, vol 3, no 11 (November 1915).
Footnote on page 118. The same text is said to have appeared in issues as far back as 1913.

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