List of Illustrations

Fig 1. The Sun. Hydrogen Spectroheliogram. (J. Evershed)

Fig 2. Solar Vortices. Hydrogen Spectroheliogram. (Mount Wilson Observatory)

Fig 3. Tracks of Alpha Particles (helium atoms). (C. T. R. Wilson)

Fig 4. Tracks of Beta Particles (electrons). (C. T. R. Wilson)

Fig 5. Ionization by X-rays. (C. T. R. Wilson).

Fig 6. Ions produced by Collision of a Beta particle (C. T. R. Wilson)

Fig 7. The Mass-luminosity Curve

Fig 8. The Ring Nebula in Lyra. Slitless Spectrogram. (W. H. Wright)

Fig 9. Flash Spectrum of Chromosphere showing Head of the Balmer Series. (British Eclipse Expedition, 14 Jan. 1926)

Fig 10. Solar Prominence. (British Eclipse Expedition, 29 May 1919)

Fig 11. Star Cluster Centauri. (Cape Observatory)