INTRODUCTION 21 



where astronomers have been able to anticipate, deduc- 

 tively, the revelations of the telescope, the spectroscope 

 and the bolometer. Thus, Jupiter and Saturn were be- 

 lieved to be ice-cold until the telescope showed them to 

 be hot ; the Martian canals were a complete surprise, and 

 until the first edition of this work appeared that planet 

 was assumed to be arid, whereas he is now known to be 

 well provided with oceans and clouds ; the full moon was 

 believed as a matter of course to be roasting hot, till 

 Langley's bolometer proved it to be intensely frigid, and 

 so on. Surely the aim of science is to interpret Nature 

 by the exercise of our reason and intelligence, not to 

 stare her out of countenance by main force. 



STELLAR PROBLEMS 



Very much the same sort of criticism may be made 

 respecting the present scientific methods of dealing with 

 the problems presented by the stars. Nothing could ex- 

 cel the care, skill and industry with which astronomers 

 have performed the drudgeries of observational investi- 

 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 1 What is the origin of 

 the nebulse? 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 



