Recollections of seventy years of scientific work

Abstract

This article records some of the researches in solar physics undertaken during my life. These have included the following: prominence observations covering sixteen years; spectroheliograph work with a direct vision prism; experiments on the radiation of heated gases; eclipse expeditions in 1898 and 1900; studies of the relation between emission and absorption spectra, and of the continuous spectrum of hydrogen. In India (1906–1923) my work included: the discovery of radial motion and the estimate of pressure in sunspots; a study of the exceptional observing conditions in Kashmir; measurements of the red-shift in connection with Einstein's prediction; great magnetic storms during flares; the motion in the tail of Halley's comet and its transit over the Sun; observations of novae. At Ewhurst (1923–1954) I was concerned with: high-dispersion work with liquid prisms; the study of the Zeeman effect and the discovery of a particularly sensitive line for its determination; measurements of minute line-shifts due to horizontal motions; and the decrease of wavelength of solar lines. Reference is made to scientific men I have met and to whom I am indebted for interest and encouragement.