Page:Popular Science Monthly Volume 76.djvu/9

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THE

 

POPULAR SCIENCE

 

MONTHLY



JANUARY, 1910



HALLEY'S COMET
By Professor C. L. DOOLITTLE
THE FLOWER ASTRONOMICAL OBSERVATORY

IN what will be said in this connection respecting comets in general and Halley's comet in particular, it will not be necessary to occupy much space in repetition of the well-known series of ancient views respecting the physical nature of these bodies or the superstitious dread with which they were regarded. With reference to the latter phase of the subject it may be said in passing, that it was not altogether an unfortunate matter, as without this incentive, probably even such fragmentary and unsatisfactory records of comets as have come down to us would not have existed.

These accounts are very seldom of much service from a scientific point of view. Very few seem ever to have thought it worth while to measure the position of a comet, or to record anything that would help us to-day in the determination of its orbit, or in identifying it with earlier or later appearances. It was believed that they were meteoric in character, occurring like the aurora borealis only a few miles perhaps above the earth's surface, and subject to no uniform laws like the heavenly bodies. This applies to the western nations simply. We shall see that the Chinese were at least a little more rational in their methods, though little as to their ideas on this branch of astronomy is known. There are, however, among the ancient writers, two whose utterances regarding comets are worthy of some attention, Diodorus Siculus and Seneca. The former wrote a voluminous universal history in which matters of authentic history are indiscriminately jumbled with myth and fiction, all apparently being considered of equal value. Among these, this statement occurs. "The ancient Egyptians and Chaldeans derived from long series of observations, methods for predicting the appearance of comets." As earthquakes and hurricanes were also occurrences which they were said to be able to predict, it seems to be the