There is a very singular appearance seen upon the sun which must not be passed over without mention. Some astronomers speak of the whole surface as being _mottled_ all over with a curious rough look when examined through a powerful telescope. This “mottling” is described by various observers in various ways. One speaks of “luminous spots shaped like rice-grains.” Another, of “luminous spots resembling strokes made with a camel’s-hair pencil.” Another, of “luminous objects or granules.” Others, of “multitudes of leaves,” “nodules,” “crystalline shapes,” “leaves or scales, crossing one another in all directions, like what are called spills in the game of spillikens.” They have also been pictured as “certain luminous objects of an exceedingly definite shape and general uniformity of size, whose form is that of the oblong leaves of a willow-tree.” These cover the whole disk of the sun, excepting the space occupied by the spots, in countless millions, and lie crossing each other in every imaginable direction. In size they are said to be about one thousand miles long, by two or three hundred broad, but they vary a good deal. Where there is a spot, the willow-leaves at its edge are said to point pretty regularly towards the center. Whether they are, as they seem to be, solid in form; whether they are, as some suppose, the chief source of the sun’s light and heat; whether they lie on his surface or float in his atmosphere; what is their real nature, and what is their real use,--about these questions we are at present quite in the dark. We have next to think a little more about the edge or limb of the sun, and the stormy flames and outburst there seen. Until quite lately the only time for observing such appearances was during a total eclipse of the sun. Lately, by means of the new instrument called the “spectroscope,” it has been found possible to take observations when no eclipse is going on. [Illustration: SUN-FLAMES, MAY 3, 1892.] A few words of explanation as to eclipses of the sun seem needful, before going further. An eclipse of the sun is caused simply by the round body of the moon passing exactly between the sun and the earth, so as to hide the sun from us. Let there be a candle on the table, while you stand near. The rays of light from the candle fall upon your face. Now move slowly, to and fro, a round ball between you and the candle. So long as it is not precisely in the line between--so long as it is a little higher, or a little lower, or a little to one side--then you can still see the flame. Once you let the ball come just between the light and your eyes, and you see it no more. In other words the candle-flame is eclipsed--hidden, veiled, cut off--by the ball.