Abstract
LONDON. The Optical Society, Oct. 15.—F. Twyman and A. Harvey: The validity of the Schwarzschild relation as applied to the use of the logarithmic sector. A direct experimental test is made of the Schwarzschild relation as applied to the logarithmic sector used in conjunction with a quartz spectrograph. The relation is found to hold within the limits of the experiments, from which it follows that the length of a spectral line on the photographic plate is proportional to the logarithm of its intensity.—F. Twyman: The ‘Spekker’ photometer for ultra-violet spectrophotometry. With the original Hilger sector photometer a glass disc was supplied, with its absorption curve in the ultra-violet. This was to enable a calibration of the sector to be made on each photographic plate, and thus to avoid errors due to any assumption concerning the Schwarzschild constant. Although the original rotating sector withstood the criticisms levelled against it on the score of intermittency, there were a number of real objections to its use. The photometer described in the present paper is now made by Adam Hilger, Ltd., under the trade mark ‘Spekker’. The risk that the intensity of illumination from the two aspects of the light source may be unequal is overcome by the use of two rhombs.
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Societies and Academies. Nature 128, 770 (1931). https://doi.org/10.1038/128770a0
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DOI: https://doi.org/10.1038/128770a0