^0 



Analysis enables us to tread with firm step in regions of nature, which 

 previously might well have been regarded as absolutely inaccessible ; 

 light is as true a messenger as sound, and in some respects we become 

 as conversant with what is going on in the remote regions of the universe, 

 as if we had correspondents in those regions who could report to us viva 

 voce. 



By this method of investigation we can assert that a variety of sub- 

 stances known upon the earth's surface are to be found in the sun ; for 

 example, iron, magnesium, manganese, cobalt, chromium, sodium, 

 titanium, calcium have been identified. And it has been further proved 

 that the sun emits from its surface grand jets of blazing hydrogen gas, 

 some 70,000 miles high. 



There is still another application of this kind of analysis, which I 

 will not tax your patience by endeavouring to explain, but the results of 

 which are so curious that I may well refer to them. It is possible by the 

 examination of the light coming to us from a certain distant body to 

 ascertain whether that body keeps its distance from us, or whether it is 

 approaching or receding. By observations made upon the well-known 

 star Sirius, commonly called the Dog Star, it has been shown that the 

 distance between that star and the sun is increasing at the rate of about 

 20 miles a second. This increase of separation has apparently been 

 going on ever since Sirius was first known and observed, and yet there is 

 no evidence that the apparent brightness of that star has been perceptibly 

 diminished. I need hardly say what a magnificent conception is thus 

 given us of the enormous grandeur of Sirius, regarded as a luminous 

 body. 



But I pass away from this fascinating subject, merely adding that 

 the spectrum analysis is almost in its infancy, and that it is impossible 

 even to guess what may be the extent of direct knowledge in store for us 

 with regard to the heavenly bodies, whether stars, planets, or comets, 

 and with regard to phenomena such as the Aurora Borealis, to which an 

 investigation by means of light is applicable. The limits of scientific 

 knowledge, if limits there be, are certainly very far from being yet 

 reached. Newton was nearer to the truth, than perhaps even he with his 



