very recent period. Millions of worshippers for ages hailed the rising sun, or bowed their faces at his setting; and yet these spots seem never to have been observed, though quite noticeable often by the naked eye. One would almost be inclined to conclude that they are a modern feature of the sun, were it not that we have many parallel cases, where obvious facts have been overlooked for successive generations. The experience of most people will corroborate this fact from their own experience. How few have actually seen a spot on the sun, though every person must have had many opportunities of observing them! There is no town so favourably circumstanced for the observation of the spots as Glasgow. The cloud of smoke that usually hangs over it, mingled with the fog of the river, affords an admirable darkening medium for viewing them with comfort. Yet how few of the inhabitants have seen them, though there are few days in winter which do not present favourable opportunities for noticing objects often so conspicuous to the naked eye.
It was probably the advantages of the murky atmosphere of Glasgow that led Dr Wilson, the discoverer of the nature of the spots, to direct his attention to the subject. His theory is now almost universally adopted, though the recent results of spectrum analysis will probably lead to some modification. The spots are perforations in the luminous envelope of the sun, through which we see its dark body. This envelope or photosphere may be conceived as
