THE 



POPULAR SCIENCE 



MONTHLY. 



FEBRUARY. 1903- 

 THE SCIENCE OE ASTKONOMY.* 



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 con- 

 siderable accuracy. His periods are : 



Period. Error X 100 

 Period 



Mercury 87d .9698 + (M .0007 



Venus 224.7028 + 0.0009 



Earth 365.2599 + 0.0010 



Mars 686.9785 0.0002 



Jupiter 4332.3192 0.0061 



Saturn 10758.3222 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 



* Address of the President of the American Association for the Advance- 

 ment of Science, Washington meeting, December 29, 1902. 



