Page:Popular Science Monthly Volume 76.djvu/11

method of procedure to attempt to find similar cycles for other natural phenomena.

In view of the apparent facility with which the cycles, real or imaginary, can be discovered by those who have a taste for such investigations, we can readily believe that the occurrences referred to were thought to fall into line, and that predictions for the future may have been attempted. It is well to remember, in this connection, that no inconsiderable part of the science of to-day is in a similar empirical status. I need only to mention the sun-spot cycle, or cycles of which there are two or three, more or less fully established, and which depend wholly upon observation. Regarding the underlying causes, we perhaps know as little as the Babylonians did of the nature of comets. The numerous attempts which are still made to fit the various phenomena of the weather into some such orderly scheme are not all confined to the ranks of the ignorant and mentally unbalanced.

The second writer alluded to, viz., Seneca, makes, what was for his time, this remarkable statement:

Why should we be surprised that comets, phenomena so seldom presented to the world, are for us not yet submitted to fixed laws, and that it is still unknown from whence come and where remain these bodies whose return takes place only at immense intervals? Fifteen centuries have not elapsed since

Greece counted the stars by their names.

How many people at the present day know nothing of the heavens except their aspect, and can not tell why the moon is eclipsed and covered with darkness! We ourselves in this matter have but lately attained to certainty. An age will come when that which is mysterious for us will have been made clear by time and by the accumulated studies of centuries. For such researches the life of one man would not suffice were it wholly devoted to the examination of the heavens. How then should it be, when we so unequally divide these few years between study and vile pleasure? The time will come when our descendants will wonder that we were ignorant of things so simple. Some day there will arise a man who will demonstrate in what region of the heavens comets take their way; why they journey so far apart from other planets, what their size, their nature. Let us, then, be content with what is already known; let posterity also have its share of truth to discover.

It was during the middle ages that the wildest absurdities regarding comets prevailed. Their connection with plague, pestilence and famine, with battle and murder and sudden death seems to have been called in question by no one. With the dawn of the renaissance, more rational notions began to appear. At first slowly, as we might expect.

One of the first to take hold of the problem in something approaching a scientific fashion, was the renowned Tycho Brahe, 1546–1601. From observations of his own he proved that comets were heavenly bodies, certainly as distant as the moon, instead of mere atmospheric phenomena, as was commonly supposed. With regard to their orbits, however, he was far from the truth in supposing them circular. Kepler was not so fortunate here as in his planetary investigations, supposing