OUR CHIEF TIMEPIECE LOSING TIME. 51 



track, so that when in due time the evidence offered 

 by the earth was corrected, Newton w T as prepared at 

 once to accept and propound the noble theory which 

 rendered his name illustrious. Again, men wished to 

 learn the true shape of the earth, and went hither and 

 thither measuring its globe ; but the moon, meanwhile, 

 told the astronomer who remained at home a truer 

 tale. They sought to learn the earth's distance from 

 the sun, and from this and that point they turned their 

 telescopes on Yenus in transit ; but the moon has set 

 them nearer the truth, and that not by a few miles, 

 but by 3,000,000 or more. "We shall see that she has 

 had something to say about our great terrestrial time- 

 piece. 



One of the great charms of the science of astron- 

 omy is, that it enables meu. to predict. At such and 

 such an hour, the astronomer is able to say, a celestial 

 body will occupy such and such a point on the celes- 

 tial sphere. You direct a telescope toward the point 

 named, and lo ! at the given instant the promised orb 

 sweeps across the field of view. Each year there is 

 issued a thick octavo volume crowded with such predic- 

 tions, three or four years in advance of the events 

 predicted ; and these predictions are accepted with as 

 little doubt by astronomers as if they were the records 

 of past events. 



But astronomers are not only able to predict they 

 can also trace back the paths of the celestial bodies, 



