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162 own and his father's keenness in viewing it till the heat affected their eyes, of his extreme impatience till morning again revealed to him in the sun itself what he thought was only a cloud, and of the incredible delight with which he welcomed the strange stain on the sun's brightness, but removed a little from the place where it was seen the day before—he tells a true story with the pen of a romancer inventing a world of wonders. The darkened room, the hole in the shutter, the sheet of white paper to receive the bright image, and the sun's rotation on his axis then burst upon the world in his pages.

Some imagined that these vast fields of darkness were smoke from gigantic volcanoes on the sun; others considered them to be a mighty expanse of scum floating on a burning ocean, or dark clouds swimming in highly heated gas. But Herschel's telescope told him they were immense pits dug somehow in the shining and fiery brightness, while waves of fiercer brightness surged round the edges in crests of vast height, for which the name faculæ, or torches, had been long before invented. Over many million of square miles of the sun's surface this rising of fiercely heated waves and this digging out of black hollows were continually going on in a greater or lesser degree. As many as forty of the latter were once seen by Herschel, when he was watching Mercury, so to speak, picking his way amongst them during his passage across the sun's disc. Other observers laid claim to counting no fewer than fifty at one and the same time. What were they? In July 1643 Hevelius saw a procession of spots and bright crests more than a third of the sun's surface in