us. This principle suggested a new method as a rehable test of 

 the approach or recession of a star and of its velocity, and has 

 been applied as the basis of the new system already alluded to. 

 By measurement of the small shift of the lines in the stars spec- 

 trum from their true position as compared with the position of the 

 lines in the spectra of corresponding terrestrial substance, the 

 speed of the star's motion can be accurately ascertained. 



Brilliant results have accrued from the application of this 

 principle in conjunction with steller photography. Mr. Keller, of 

 the Lick Observatory, has applied this method to the star Arcturus, 

 the greatest discrepancy between his calculations being only three 

 tenths of a mile per second in the course of the three nights. At 

 the same time five photographic determinations of Arcturus were 

 made at the Potsdam Observatory, and the means of these five 

 determinations agreed with Mr. Keller's observations at Lick to 

 within one-tenth of a mile — a substantial proof ol the marvellous 

 accuracy of r-his new system of measurement. 



Mr. Keller has also applied this novel method in his observations 

 of the nebulfe, and found that, like the stars, they possess con- 

 siderable motion through space, the speed varying from two to 

 twenty-seven miles per second, with the exception of one, which 

 attained the velocity of forty miles per second. He found that the 

 nebula in Orion was receding at the rate of ten miles per second. 

 This spectroscopic method of observing the motion of the heavenly 

 bodies has also been most successfully applied in detecting binary 

 stars, but time will not permit of my entering into further details 

 this evening of this engrossing subject. When we consider the 

 brilliant results achieved by means of the spectroscope in the 

 course of the last thirty years, a boundless vista opens before us, 

 in which new and hitherto undreamt of discoveries await us — a 

 way. indeed, has been opened into the unknown which surpasses 

 the fondest hopes of the enthusiast. To quote Dr. Higgins's own 

 words, " to analyse the chemical nature of a far distant body by 

 means of its light alone, to be able to reason about its present state 

 in relation to the past and future, to measure within an English 

 mile or less per second the otherwise invisible motion which it 

 may have towards or from us ; to do yet more than this, so as to 

 make that which is apparent darkness become ligh*^, and from 

 vibrations which our organs of sight are powerless to perceive to 

 evolve a revelation in which we see mirrored sf me of the stages 

 through which the stars may pass in their slow evolutional pro- 

 cess — these achievements are surely such that their recurd, how- 

 ever poor the form of words, is worthy to be regarded as the 

 scientific epic of this century." 



After the usual vote of thanks the Secretary read the Rules 



