In 1922 St. John and Nicholson investigated the spectrum of Venus by photographing with a plane-grating spectrograph regions near X5900, the a-band of oxygen near X6300, and the B-band of oxygen at X6867. The radial velocity of the planet and the dispersion employed were sufficient to separate planetary lines from those of terrestrial origin. No trace was found of lines due to oxygen or to water vapor in the spectrum of the planet.
Recent progress at the Research Laboratory of the EastmanKodak Company in sensitizing photographic plates to the infra-
1' The greater part of the results described under the heading "preliminary work" were obtained by Mr. J. T. Thompson, who was forced to discontinue his studies in May, 1922, on account of severe illness. The present writer took up the work in the autumn of that year.
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