Soon after that they discovered that comets all had more or less periodicity. Nobody knows how they got it. All the astronomers had been watching them day and night and didn't know when they were exposed, but there was no time to talk and argue over the question. There were two or three hundred comets all down with it at once. It was an exciting time.
Comets sometimes live to a great age. This shows that the night air is not so injurious to the health as many people would have us believe. The great comet of 1780 is supposed to have been the one that was noticed about the time of Caesar's death, 44 B.C., and still, when it appeared in Newton's time, seventeen hundred years after its first grand farewell tour, Ike said that it was very well preserved, indeed, and seemed to have retained all its faculties in good shape.
Astronomers say that the tails of all comets are turned from the sun. I do not know why they do this, whether it is etiquette among them or just a mere habit.
A later writer on astronomy said that the substance of the nebulosity and the tail is of almost inconceivable tenuity. He said this and then death came to his relief. Another writer says of the comet and its tail that “the curvature of the latter and the acceleration of the periodic time in the case of Encke's comet indicate their being affected by a resisting medium which has never been observed to have the slightest influence on the planetary periods.”
I do not fully agree with the eminent authority, though he may be right. Much fear has been the result of the comet's appearance ever since the world began, and it is as good a thing to worry about as anything I know of. If we could get close to a comet without frightening it away, we would find that we could walk through it anywhere as we could through the glare of a torchlight procession. We should so live that we will not be ashamed to look a comet in the eye, however. Let us pay up our newspaper subscription and lead such lives that when the comet strikes we will be ready.
{Illustration: TYCHO BRAHE AT WORK.}
Some worry a good deal about the chances for a big comet to plow into the sun some dark, rainy night, and thus bust up the whole universe. I wish that was all I had to worry about. If any respectable man will agree to pay my taxes and funeral expenses, I will agree to do his worrying about the comet's crashing into the bosom of the sun and knocking its daylights out.
THE SUN.