Masterpieces of Science 



only, but of nebulas and many stars, and find in 

 meteoric collisions the explanation of a whole 

 host of the most interesting and beautiful of 

 astronomical phenomena. 



As to the stars, it is sure that the coming cen- 

 tury will bring an immense increase of knowl- 

 edge. It will be rash to endeavour to predict 

 just along what lines and to what extent the 

 development will take place; the problems are so 

 numerous and so intricate, and their successful 

 investigation depends so much on the improve- 

 ment of our means of observation and calculation, 

 that no one can say which will first be solved. 

 As in the case of the sun, mere lapse of time will 

 settle many questions. It will accumulate 

 knowledge as to the motions of the stars, and of 

 the solar system among the stars, and also of 

 the motions of the components of double stars, 

 of multiple stars and clusters; and will ultimately 

 determine with certainty whether the same law 

 of gravitation which rules the planetary system 

 prevails also in stellar space. It will give us 

 data as to the variability of the light of stars, 

 and probably will clear up the causes of it. It 

 will ascertain how, if at all, the nebulae change 

 their form and brightness, and how, if this really 

 be the case, stars develop within them, and the 

 nebula becomes a cluster. 



But how rapidly this knowledge will be gained 



must, of course, depend on many things; one 



dares not prophesy. And yet it is certain that 



the astronomers of the century to come will 



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