PRESIDENTIAL ADDRESS, B.A. 1871. 189 



The spectrum te.st of velocity applied by Lockyer 

 showed but a twentieth part of this amount as 

 the greatest observed relative velocity between 

 different vapours in the Sun's atmosphere. 



At the first Liverpool Meeting of the British 

 Association (1854), in advancing a gravitational 

 theory to account for all the heat, light, and 

 motions of the universe, I urged that the immedi- 

 ately antecedent condition of the matter of which 

 the Sun and planets were formed, not being fiery, 

 could not have been gaseous ; but that it probably 

 was solid, and may have been like the meteoric 

 stones which we still so frequently meet with 

 through space. The discovery of Huggins, that 

 the light of the Nebulae, so far as hitherto sensi- 

 ble to us, proceeds from incandescent hydrogen and 

 nitrogen gases, and that the heads of comets also 

 give us light of incandescent gas, seems at first 

 sight literally to fulfil that part of the Nebular 

 hypothesis to which I had objected. But a solu- 

 tion, which seems to me in the highest degree 

 probable, has been suggested by Tait. He 

 supposes that it may be by ignited gaseous 



