66 



the corresponding lines of the comparison spec- 

 trum, we know that the star is moving away from 

 the earth at a velocity proportional to the amount 

 of the shift. Displacement toward the violet 

 means motion toward the earth. This method, 

 first applied on a large and comprehensive plan by 

 Campbell, of the Lick Observatory, gave the ve- 

 locities of 1,500 stars and yielded many conclusions 

 of great importance. The 6o-inch reflector has 



Fir,. 49. Spectrum of Lalande 1966, showing velocity of 325 km. per 

 second toward the Karth. Position of lines in stellar spectrum 

 and of corresponding lines in comparison spectrum indicated at 

 bottom. 



enabled us to extend such measures to many fainter 

 stars. A discussion of the resulting velocities 

 shows that Kapteyn's two star-streams extend 

 into space much farther than the original data 

 (for nearer stars) permitted them to be traced. 

 1 hus the view that the main body of the universe 

 is constituted of these streams receives added 

 support. 



STARS OF HIGH VELOCITY. 



Kapteyn and Campbell independently found 

 that the radial velocities of the stars, corrected for 

 the sun's motion, range from about 6 kilometers 



