CHARTING THE UNIVERSE 



be so distant from the earth that the light coming 

 from it at the rate of about 186,000 miles per second 

 has required many years to reach us. So it is pos- 

 sible to measure the radial speed of multitudes of 

 stars that are too 'distant to show any parallax or to 

 have their shift of position across the line of sight 

 observed even by the most delicate methods. For 

 many years Professor W. W. Campbell, Director of 

 the Lick Observatory, devoted a large amount of 

 time to testing the speeds of stars with the famous 

 Mills spectrograph. In 1911 he was able to generalize 

 his results, and to show that the large number of 

 stars observed, when tested by their speed, tend to 

 fall into interesting and suggestive groups. There 

 were some complications and seeming inconsisten- 

 cies, as there usually are when human observation of 

 complex facts is in question, but, viewing the data 

 as a whole, this highly interesting and utterly unex- 

 pected generalization seems to stand forth: "The 

 older a star is, the quicker it moves." 



It had long been known that there is great vari- 

 ation in the speed of stars. Our sun, for example, 

 with its planetary attendants, is moving through 

 space at the rate of 12 or 13 miles a second; whereas 

 there are stars that are observed to move upward of 

 200 miles a second. But hitherto there had been 

 nothing to suggest that the difference in speed was 

 in any wise related to the age of the stellar body. 

 Therefore Professor Campbell's observations came 

 as an entire surprise to the astronomical world. A 

 new coign of vantage, so to speak, was supplied 

 from which to gain a glimpse into that great ultimate 



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