In Vol. 27, No. 5, May 20, 1944, page 403, in the eighth line from the bottom of the page, the comma after "intensity" should be a semicolon.

On page 413, in the second formula from the bottom of the page, for

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read

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On the same page, formula 2 should read

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On page 414, line 3, at the end of the line add "or" to read "of the level of I or of F."

On page 422, in the first line below the figure legend, for "illuminate" read "illuminated."

On page 430, line 22, for "lighteb dars" read "lighted bars."

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