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164 joined together, making waves, or waving lines." In 1801 he had advanced to the "strong suspicion that one half of our sun is less favourable to a copious emission of rays than the other; and that its variable lustre may possibly appear to other solar systems, as irregular periodical stars are seen by us" In the same paper he records in his observations that he counted at one time 45 "openings" or spots, on the following day 50, and three days later above 60. A cloud, hanging over one of these openings, was seen to move a third of the way across the mighty chasm in fifty-eight minutes.

Herschel's theory of the sun then may be thus stated. There is first the region of "luminous solar clouds" which, adding also the elevation of the faculæ, cannot be less than 1843, nor much more than 2765 miles in depth. These solar clouds he compares in density with the aurora borealis of our skies. Underneath this envelope of brightness is the sun's atmosphere, which may be so clouded as to shield the body of the sun and the beings, who live there, from the intense heat and glare above. The body of the sun lies still lower, and "is diversified with mountains and valleys." Some may deem it the horrid abode of lost souls; others may see in its cool retreats the home of blessed spirits. But so imbued is man's mind with the idea of unbearable heat in the sun that, in a court of law, belief in its coolness was at that time quoted as a proof of insanity, and of incompetence in a man to manage his own affairs. This, in short compass, is Herschel's view of the constitution of the sun. It is largely founded on the theory of his friend Wilson, the Professor of Astronomy in the University of