74 LIGHT SCIENCE FOR LEISURE HOURS. 



one in the Great Bear which presented some very 

 striking features. Five stars in this constellation, 

 known as Beta, Gramma, Delta, Eta, and Zeta, were 

 seen to be travelling, not merely at the same rate and 

 in the same direction, but on a course precisely oppo- 

 site to that which they would have had if their apparent 

 motion had been due to the sun's motion in space. 

 Moreover, all these stars are large and conspicuous ; 

 while one of them, Zeta, is distinguished by having 

 two companions, one very close to it, and the other so 

 far away that its motion around Zeta is only completed 

 (according to Madler's computation) in a period of 

 about 2,000 years ; so that, if all the five large stars 

 form a single system, the cyclic revolutions of the 

 system must require millions of millions of years for 

 their completion. 



I selected this family of stars as affording a con- 

 venient means of testing (crucially) the accuracy of 

 my theory of star-drift. If that theory is just, all 

 these stars must be either approaching or receding at 

 a common rate. If the theory is unsound, the chances 

 are enormous against their possessing a common motion 

 of approach or recession. I expressed a strong feeling 

 of confidence that whenever Dr. Huggins applied the 

 new method of research to these stars, he would find 

 that they are either all approaching or all receding, 

 and at one and the same rate. When I expressed this 

 opinion, I knew that before many months had passed, 

 the matter would be decided one way or the other. 



Nothing could be more complete than the confirma- 



