Seen during an eclipse, these prominences have clear, sharp outlines, and are usually bright rose-red in color. They are described as sometimes wide and low, sometimes tall and slender; sometimes jagged, sometimes regular; sometimes keeping long the same shape, sometimes changing quickly in a few minutes. They are said to be like flames, like mountains, like the teeth of a saw, like icebergs, like floating cloudlets. As to their height, from fifty to eighty thousand miles is nothing unusual. We must not speak of Mont Blanc or Mount Everest here. Jupiter placed bodily on the surface of the sun, beside such a fire-mountain, would not far overtop it. The earth, Venus, Mars, and Mercury, would lie like little toy-balls at its foot. And these are common-sized sun-flames. One was measured which reached to the enormous height of two hundred thousand miles. The spectroscope shows these solar prominences or jets to be made--at least in part--of burning hydrogen gas. Beyond the sierra or chromatosphere--that border of rippling, crimson flame-billows round the edge of the sun, with red flame-mountains rising out of it here and there--beyond these, stretches the corona. The corona, as seen from earth, is a bright, far-reaching glory of light, shining round the sun in a total eclipse. The moon then comes between the sun and the earth, her dark, round body creeping over the face of the sun till the bright photosphere is completely covered. But the sierra and the tall, red flames stand out from behind the black moon, and the beautiful, soft corona-light stretches far beyond. [Illustration: SOLAR CORONA AND PROMINENCE.] It was long doubted whether the corona really belonged to the sun or to the moon. There seems now no doubt that it is a part of the sun. Various descriptions of the corona have been given at different times, as observed during different eclipses. It has been seen as a steady, beamy, white cloud behind the moon, showing no flickering. It has been seen marked with bright lines of light, and seeming to move rapidly round and round. It has been seen silvery white, sending off long streams of brightness. It has been seen in the form of white light, with bluish rays running over it. It has been seen with entangled jets of light, like “a hank of thread in disorder.” It has been seen silvery-white again, with a faint tinge of greenish-violet about the outer edge. It has been seen from a high mountain-top as a mass of soft, bright light, “through which shot out, as if from the circumference of the moon, straight, massive, silvery rays, seeming distinct and separate from each other, to a distance of two or three diameters of the lunar disk, the whole spectacle showing as upon a background of diffused, rose-colored light.”