It is far more likely that this star encountered an enormous stream of meteoric bodies, or perhaps absorbed a whole comet, that laid its million leagues of tail as fuel on the central fire.  Only let it be remembered that the fuel is far more force than substance.  Allusion has already been made to the sudden brightening of our sun on the first day of September, 1859.  That was caused, no doubt, by the fall of large meteors, following in the train of the comet of 1843, or some other comet.  What the effect would have been, had the whole mass of the comet been absorbed, cannot be imagined.

Another new star lately appeared in Cygnus, near the famous star 61—­the first star in the northern hemisphere whose distance was determined.  It was first seen November 24th, 1876, as a third magnitude star of a yellow color.  By December 2d it had sunk to the fourth magnitude, and changed to a greenish color.  It had then three bright hydrogen lines, the strong double sodium line, and others, which made, it strongly resemble the spectrum of the chromosphere of our sun.  An entirely different result appeared in the fading of these two stars.  In the case of the star in the Crown, the extraordinary light was the first to fade, leaving the usual stellar spectrum.  In the case of the star in Cygnus, the part of the spectrum belonging to stellar light was the first to fade, leaving the bright lines; that is, the gas of one gave way to regular starlight, and the starlight [Page 226] of the other having faded, the regular light of the glowing gas continued.  By some strange oversight, no one studied the star again for six months.  In September and November, 1877, the light of this star was found to be blue, and not to be starlight at all.  It had no rainbow spectrum, only one kind of rays, and hence only one color.  Its sole spectroscopic line is believed to be that of glowing nitrogen gas.  We have then, probably, in the star of 1876, a body shining by a feeble and undiscernible light, surrounded by a discernible immensity of light of nitrogen gas.  This is its usual condition; but if a flight of meteors should raise the heat of the central body so as to outshine the nebulous envelope, we should have the conditions we discovered in November, 1876.  But a rapid cooling dissipates the observable light of all colors, and leaves only the glowing gas of one color.

Movements of Stars.

We call the stars fixed, but motion and life are necessary to all things.  Besides the motion in the line of sight described already, there is motion in every other conceivable direction.  We knew Sirius moved before we had found the cause.  We know that our sun moves back and forth in his easy bed one-half his vast diameter, as the larger planets combine their influence on one side or the other.

The sun has another movement.  We find the stars in Hercules gradually spreading from each other.  Hercules’s brawny limbs grow brawnier every century.  There can be but one cause:  we are approaching that quarter of the heavens. (See [Symbol], Fig. 72.) We are even [Page 227] able to compute the velocity of our approach; it is four miles a second.  The stars in the opposite quarter of the heavens in Argo are drawing nearer together.