INTRODUCTION 11 



gation and mathematical computation, bringing virtually 

 to a state of repletion the stock of ascertainable data 

 wherewith to erect a sound and comprehensive urano- 

 graphy. Just here, however, is where their progress 

 halts. The workmen have indeed provided and delivered 

 to hand the building materials, but the architect has been 

 wanting. What we want to know, and what astronomers 

 cannot tell us, is, how this plethora of material is to be fit- 

 ted together ? We want to know, specifically, such things 

 as these : 



Is there a universe beyond our own? What is the 

 meaning of the great aggregation of stars in the Milky 

 Way? Why are so many millions of the stars contempor- 

 aneously brilliant? Is there any rule by which we can de- 

 termine the intrinsic sizes of stars ? What is the origin of 

 the nebulae? Why do they rotate? What is the explan- 

 ation of their diversity of form? Why do the velocities 

 of stars vary according to their spectral class ? Are the 

 stars all alike in chemical composition? How do they, in 

 spite of gravity, preserve themselves aloof from one an- 

 other? Why do "maturer" systems revolve more rapidly 

 than those more youthful? Is there acentral sun? Is there 

 a maximum size to which star scan attain? What is the ex- 

 planation of star streams? Why is the radius of the celes- 

 tial circle of precession the same as the inclination of the 

 earth's axis? What produces the sun's flight in space? 

 What are the elements of its orbit? 



To all such questions, elementary though they are, 

 contemporary science returns no answers save of ad- 

 mitted speculation. 



THE DESTINY OF THE UNIVERSE 



From the standpoint of general philosophy probably 

 the chief cosmological query is as to the permanency or 

 impermanency of the Present Order. According to the 

 hierarchy of modern science, this order is not permanent, 

 the great cosmic machine is "running down", and it is 

 only a question of time till it shall destroy itself. College 



