Letter | Published:

A Helium Series in the Extreme Ultra-Violet

Nature volume 104, page 393 (18 December 1919) | Download Citation



IN NATURE for November 20 Prof. Lyman reports his observation of a helium line at 1640.1, as well as a weak one at 1215.1, close to the strong one 1216, and refers them to orders 3, 4 in the series 4N{1/22-1/m2}. If the correct reading for the strong line is nearer the 1215.1, the whole series m=4 … 8 is found in his list of ultra-violet lines given in the Astro. Journ. (vol. xliii., p. 89, 1916). The following is the list of observed lines with deviations (obs.–calc.) from the calculated values, with N = 109720:—

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  1. Crowhurst, December 11.

    • W. M. HICKS


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