316 the president's address. 



discoverer of the dark lines in 1 802 could have had no conception. 

 Few can realize how important, in a scientific point of view, 

 these investigations have become ; for it is solely from these 

 simple coincidences of lines in different classes of spectra, that 

 all the inferences and theories that have emanated from the 

 philosopher's brain, in relation to this subject, have been 

 derived. 



What is a star ? The answer that I may briefly give to this 

 question must be, in some measure, of a speculative nature. In 

 all probability, most of the fixed stars visible to the naked eye, 

 and also others that are strictly telescopic, are incandescent 

 bodies shining by their own intrinsic light, each forming 

 possibly the central sun of a planetary system. But you may 

 naturally ask me on what theory such a romantic proposition can 

 be sustained. My answer would be that observation has shown, 

 with great certainty, that several of the visibly double and 

 triple stars are stellar systems, proved to be in physical harmony 

 by the revolution of the separate members of the group round 

 one common centre of gravity ; and this connection is so well 

 established that the elements of their orbits are accurately calcu- 

 lated for a large number of these binary and ternary stars. But, 

 as I have before said, it is very remarkable that in all the 

 twinkling stars of different magnitudes, whose spectra have been 

 examined, sufficient evidence has been gathered to show that the 

 substances of which they are composed bear a strong affinity to 

 the constitution of some of the existing organisms of our own 

 earth, including iron, sodium, hydrogen, magnesium, and other 

 substances. It has been stated by Dr. W. Huggins, F.R.S., and 

 Prof. W. C. Miller, F.R.S., in a joint communication to the 

 Royal Society, that "these forms of elementary matter, when 

 influenced by heat, light, and chemical force, all of which we have 

 certain knowledge are radiated from the stars, afford some of the 

 most important conditions which are known to be indispensable 

 to the existence of living organisms such as those with which we 

 are acquainted." It may be concluded, therefore, as a very 

 probable consequence, " that at least the brighter stars are, 

 like our sun, upholding and energizing centres of systems of 

 worlds adapted to be the abodes of living beings." 



