zo THE POPULAR SCIENCE MONTHLY. 



Now, the question which Las agitated astronomy during the past 

 few years has been simply whether the glory of light seen around the 

 sun is in reality a solar appendage, or may not be due wholly or in 

 part to the illumination either of our own atmosphere or of some other 

 matter (not necessarily atmospheric) lying much nearer to us than the 

 sun does. If we consider the figure, we can see at once that if we 

 have here a real solar appendage that is, matter which exists all 

 around the sun's globe it is an appendage of the most amazing ex- 

 tent. The black disk which forms the centre of the figure is of course 

 intended to represent the moon, whose diameter we know is about 

 2,200 miles, and if for a moment we suppose the corona c and R sur- 

 rounds the moon, we see that it must extend on one side to about 

 5,000 miles, and elsewhere to about 2,800 miles. But exactly behind 

 the moon lies the sun, a little more than concealed by the moon ; and 

 the sun's diameter is about 850,000 miles. So that, if the corona is 

 something which surrounds the sun, it extends, as the picture shows, to 

 at least 2,000,000 miles on one side, and elsewhere to about 1,200,000 

 miles. Neglecting the dark rifts for the moment, and regarding 

 the whole corona as shaped like a globe, and having a diameter four 

 times as great as the sun's, we should have to regard its volume as ex- 

 ceeding his not four times, nor sixteen times, but sixty-four times. 

 And when we are reminded that the sun's own volume exceeds that of 

 this earth on which we live some 1,200,000 times, we see what a stu- 

 pendous conclusion we must arrive at, if we regard the corona as a 

 solar appendage. Of course, we need not imagine that the corona has 

 a continuous substance completely filling a space some 77,000,000 

 times larger than the earth. It may be made up of multitudes of 

 minute bodies, with vacant spaces between. But the conclusion re- 

 mains that a region of space, exceeding our earth's volume so many 

 millions of times, is thus occupied by matter of some sort. 



Nor is the conclusion rendered a whit less surprising if we take the 

 dark rifts into account. Nay, we obtain an enhanced idea of the 

 wonderful nature of the corona, regarded as a solar appendage, when 

 we consider that it possesses so remarkable a structure that, as seen 

 from our distant stand-point, it shows well-defined gaps or rifts. For 

 unquestionably it is not to be regarded as something flat or plane- 

 shaped, like its picture, or a decoration (which in appearance it often 

 strikingly resembles). It must extend on all sides from the sun (if it 

 is indeed a solar appendage), and not merely from the sides of the disk 

 he turns toward us at the time of an eclipse ; and it can easily be seen 

 that its shape, in length and breadth and thickness, must be strange, 

 to account for such rifts as are shown in the figure. If we take an 

 orange to represent the sun, and, boring holes all over it, stick spills 

 in these holes to represent the region occupied by the corona, we shall 

 find that, in order that our spillikined orange may exhibit a rifted 

 corona in whatever position it is placed, we must either leave several 



