9 
us. This principle suggested a new method as a reliable test of 
the approach or recession of a star and of its velocity, and hag 
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 speetra 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 ot the marvellous 
accuracy of this new system of measurement. 
Mr. Keller has also applied this novel method in his observations 
of the nebule, 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 binar 
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 t» 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 light, and from 
vibrations which our organs of sight are powerless to perceive to 
evolve a revelation in which we see mirrored scme of the stages 
through which the stars may pass in their slow evolutional pro- 
cess—these achievements are surely such that their record, 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 
