Page:Popular Science Monthly Volume 62.djvu/297

THE

POPULAR SCIENCE

MONTHLY

FEBRUARY. 1903.

 THE SCIENCE OF ASTRONOMY.[1]
By Professor ASAPH HALL, U.S.N. (Retired).

TAKE for the subject of my address the science of astronomy, and propose to give a brief historical sketch of it, to consider its future development, and to speak of the influence of the sciences on civilization.

The science of astronomy is so closely connected with the affairs of life, and is brought into use so continuously and in such a systematic manner, that most people never think of the long labor that has been necessary to bring this science to its present condition. In the early times it was useful to the legislator and the priest, for keeping records, the times of public ceremonies and of religious festivals. It slowly grew into the form of a science, and became able to make predictions with some certainty. This was many centuries ago; Hipparchus, who lived 150 B. C, knew the periods of the six ancient planets with considerable accuracy. His periods are:

 Period. Error × 100Period Mercury 87d.9698 ${\displaystyle +}$ 0d.0007 Venus 224.7028 ${\displaystyle +}$ 0.0009 Earth 365.2599 ${\displaystyle +}$ 0.0010 Mars 686.9785 ${\displaystyle -}$ 0.0002 Jupiter 4332.3192 ${\displaystyle -}$ 0.0061 Saturn 10758.3222 ${\displaystyle -}$ 0.0083

These results indicate that more than two thousand years ago there existed recorded observations of astronomy. Hipparchus appears to have been one of those clear-headed men who deduce results from observations with good judgment. There was a time when those ancient

1. Address of the President of the American Association for the Advancement of Science, Washington meeting, December 29, 1902.