The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific (1919)
Astronomical Society of the Pacific, Aitken, Robert Grant, 1864-1951 · San Francisco Stanford University Press · leaf 246
e Sun and terrestrial phenomena. Sun-spots, faculae, and prominences increase together to a maxi-mum number, decrease to a minimum, then rise again to amaximum in regular sequence, that is, they show a definiteperiodicity. The question may be raised, Are there phenomenaon the Earth that run the… … (a) Doubling of lines in the magnetic field. (b) Doubling of line in the umbra of a sun-spot.
Astronomy
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