Abstract
THE presidential address to the Section of Mathematics and Physics at the twenty-third Indian Science Congress was delivered by Dr. T. Royds, director of the Kodaikanal Solar Physics Observatory, who took as his subject “Some Solar Problems” (Calcutta: Asiatic Society of Bengal). Dr. Royds explained that he was dealing with topics which were the subject of present research at Kodaikanal. The first of these was the relation between the dark markings, seen on spectroheliograms, and the prominences. The motion of the dark markings near the limb demonstrates that they are situated at such a height above the photosphere that they would project 31″ above the limb, whereas the average height of prominences is known to be 36″. So far as Kodaikanal observations go, the dark markings and prominences appear to be different aspects of the same thing, that is, a narrow line of flame extending above the sun's surface, having a width of 7,000 miles, a height of 14,000 miles, and an enormous length amounting sometimes to 400,000 miles. Dr. Royds went on to deal with the problem of the support of the chromosphere: it has recently been found at Kodaikanal as the result of observations of the infra-red lines near 7770 A. that oxygen is a normal constituent of the chromosphere. This fact adds to the difficulties in the path of the theory that selective radiation pressure supports the chromosphere. Dr. Royds concluded his address by giving an account of the theory of the intensities of Fraun-hofer lines and of recent measurements which have been carried out at Kodaikanal.
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Solar Research at the Kodaikanal Observatory. Nature 137, 610 (1936). https://doi.org/10.1038/137610b0
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DOI: https://doi.org/10.1038/137610b0