of the Sun itself laid bare by those immense fluctuations in the of its atmosphere, to which it appears to be

The idea of a hot surface overlying a darker interior seems quaint enough now, and did not seem to be reaDy convincing in 1903, yet Sir Robert repeated it in another book, Star/and, published in 1914. It was probably the brilliant theoretical work by Sir Arthur Eddington, in the 1920s, which caused a change of outlook, and in 1935 the then Astronomer Royal, Sir Harold

Spencer Jones, pain ted a very different picture in his book W/orlds witbout bzd:

"A sunspot is a gigantic funnel-shaped vortex in the outer regions of the Sun. Around the vortex intensely hot gas from within the Suo is whirling spirally upwards. We can compare a sunspot vortex with the hollow vortex formed by water emptying out of a bath, if we imagine the water to be made to run in the opposite direction and to stream upwards from the outlet into the bath. As the gases stream out of the funnel-shaped mouth of the vortex, the pressure which has urged them upwards is released; the emitted gases then stream more or less radially outwards from the spot along the surface, producing the radial fibrous structure seen in photographs of the penumbra of spots."