Appendix. Ixxiii 



terrestrial substances. The labour of overcoming all these diffi- 

 culties was great, but great also was the reward. To use Huggins' 

 own words : " The time was, indeed, one of strained expectation and 

 of scientific exaltation for the astronomer, almost without parallel ; 

 for nearly every observation revealed a new fact and almost every 

 night's work was red-lettered by some discovery." Time does not 

 allow me to proceed in the order of history nor to classify the work 

 done by Huggins and his successors. The spectra of vast numbers 

 of the stars were shown to be identical with those of the sun, the 

 spectra of others were less complex, of others more so, but all 

 contained evidence of the existence of chemical substances which are 

 contained in our globe. As powerful telescopes had shown many 

 objects, previously supposed to be only nebulous, to consist of 

 separate stars, the belief naturally began to be held that all nebulas 

 Avere in reality distant systems of stars which would be seen as such 

 if only adequate optical means and sufficiently clear and steady 

 atmospheric conditions were available. But Huggins' spectroscope 

 showed that many nebulse were not stars at all, that many well- 

 condensed nebulae, as well as vast patches of nebulous light in the 

 sky, gave only bright lines in the spectroscope — lines which proved that 

 such nebulae were not stars at all, but inchoate masses of luminous gas. 

 Evidence upon evidence has accumulated to show that such nebulae 

 consist of the matter out of which stars {i.e., suns) have been, and 

 are being, evolved. The different types of star spectra form such a 

 complete and gradual sequence (from simple spectra resembhng those 

 of nebulae, onwards through types of gradually increasing complexity) 

 as to suggest that we have before us, written in the cryptograms of 

 these spectra, the complete story of the evolution of suns from the 

 inchoate nebulae onwards to the most active sun (like our own) and 

 then downward to the almost heatless and invisible ball. The period 

 during which human life — nay, even life of any kind — has existed on 

 our globe is probably too short to afford observational proof of such 

 a cycle of change in any particular star, but the fact of such evolu- 

 tion, with the evidence before us, can hardly be doubted. I most 

 fully believe that when we have farther studied the modifications of 

 terrestrial spectra, under sufficiently varied conditions of temperature, 

 pressure, and environment, our certainty of the fact will be greatly 

 increased. But in this study we must also have regard to the 

 spectra of the stars themselves. The stars are the crucibles of the 

 Creator. There we see matter under conditions of temperature and 

 pressure and environment, the variety of which we can hardly hope 

 to emulate in our laboratories, and on a scale of magnitude beside 

 which the scale of our greatest experiment is less than that of the 



