There are some facts connected with our own system which make it appear not improbable that up to the time of which we are speaking the light which is now gathered up in the sun was diffused over a space in which at all events the earth’s orbit was included.  It is now a recognized fact that all the light of the system is not as yet wholly concentrated in the sun, as we generally recognize it, but that to some extent the sun is still a nebulous star.  Under ordinary circumstances we see only that circular disc, which we usually recognize as the sun.  Its surpassing brightness overpowers every thing else, whether we view it with the unaided eye or through the telescope.  But when the actual disc is hidden from us by the moon in a total eclipse, other regions of light surrounding the disc, make their appearance, and in them the most wonderful processes are continually going on.  The simultaneous discoveries of Messrs. Lockyer and Janssen, in 1868, have enabled some of these processes to be continuously watched when the sun is not eclipsed, but others can as yet only be seen during the few minutes (never amounting to seven) which a total eclipse lasts, so that as yet we know very little of them.

Immediately surrounding the disc of the sun, which is visible to the naked eye, is a brilliant ring of light, known now as the chromosphere or sierra.  This is the region which till 1868 could be seen only during total eclipses, but can now be watched at all times by means of the spectroscope.  In it symptoms of intense action are from time to time witnessed.  For many years past, whenever a total eclipse occurred, there were observed on the edge of this ring certain red prominences.  The spectroscope has revealed their nature.  They consist chiefly of enormous volumes of hydrogen, ejected from the surface of the sun with a velocity almost inconceivable, and at the same time revolving about their axis after the fashion of a cyclone. [Footnote:  Popular Science Review, January, 1872, p. 150; Look.  Byer’s Lecture on the Sun, at Manchester, 1871.] A very remarkable instance of this was observed in America in September 1871, by Professor Young.  A mass of incandescent hydrogen was propelled to a height of 200,000 miles above the visible disc; of these the last 100,000 miles were passed through in 10 minutes.  Such events, though not commonly on so vast a scale, are continually occurring on the surface of the sun, and they seem to be in close connexion with the magnetic phenomena occurring on the earth.

Beyond the chromosphere lies the corona.  The spectroscope has not yet rendered this visible at all times, and consequently we are dependent upon the information to be obtained during the few minutes of total eclipses, when alone it is visible.  Consequently during recent solar eclipses this has been the point to which the attention of astronomers has been especially devoted.  The eclipse of December, 1870, decided one point, that the corona was a truly solar phenomenon,