THE GREAT STAR MAP 



441 



repeated and the comparison rendered possible.] Now we 

 might naturally expect to find more moving stars among the 





500 than among the 50, but we do not ; there are just as many 

 per plate (that is to say on a given sky-area), in any part of the 

 sky, whether it be densely or sparsely covered with stars. It is 



29 



