H ALLEY'S COMET 7 



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 in- 

 vestigations, 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 dark- 

 ness! 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 descend- 

 ants 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 approach- 

 ing 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 



