I. Transmission of sunlight through earth’s atmosphere

Abstract

XXII.—In a previous communication (‘Phil. T rans.,' vol. 178, 1887, A., pp. 251-283) the results of the absorption of sunlight by different thicknesses of atmosphere near sea level were found from measurements of the luminosity of the entire spectrum. The method used was that devised by General Festing and the Author, as detailed in the Bakerian Lecture in 1886. The absorption coefficient for th e different thicknesses of atmosphere at sea level was found by measurements made principally at South Kensington, and these were compared with measures taken at the Eiffel, above Zermatt, at a height of about 8000 feet. It was shown that when the air thickness is represented by x , the minimum intensity for each ray of the spectrum can be fairly represented by I' = Ie- - -017 xa , and the average intensity by I' = Ie -013 xa -4 , being the transmitted and original intensities, and X the wave length.and λ the wave length.