466 Molecules, Ultimates, Atoms, and Waves. [October, 



generating such vibrations in the ethereal particles, than by 

 their vibrating themselves either at precisely the same rates 

 or at some octave of those rates. Nor could there be easily 

 assigned any other reason for their absorbing or taking 

 up the already existing vibrations of the ethereal particles 

 of those four particular periods, than by their tendency 

 to assume those rates, or some octave of them, and take up 

 the motive energy from the ether to enable them to perform 

 their movements. But in order to their vibrating at all, it 

 is needful to suppose these atoms to be not in absolute 

 mutual contact, but to be kept apart by a layer of com- 

 pressed ether, the elasticity of which exactly balances their 

 mutual attraction. Of the greatness of this attraction 

 we have two proofs — the one the degree of compression 

 which the ether undergoes under its influence; the second, 

 the great amount of applied motive energy required to 

 set the atoms a vibrating. In this particular these atoms 

 differ from the hydrogenous ultimates themselves, of which 

 they are the constituent parts. For the ultimates can be 

 made to vibrate by a very small amount of applied force ; 

 whereas their constituent atoms require the application 

 of an intense force to make them vibrate ; while, under 

 ordinary circumstances, they vibrate each kind only at 

 one particular rate. 



The foregoing views are strengthened by certain other 

 phenomena which these four spectral lines of hydrogen 

 present. Of the four, that producing the line f is by much 

 the most conspicuous. Those near g and h are com- 

 paratively feeble, and require a higher temperature for their 

 development. When strong pressure is applied, it is the 

 line f that first manifests a decided increase in breadth ; 

 and it is by the gradual widening of the four lines, but 

 especially of f, that the hydrogen spectrum ultimately be- 

 comes, under a very strong pressure, continuous like that 

 from an incandescent body. This phenomenon, which would 

 be nearly inexplicable on the supposition that the ultimates 

 of hydrogen are simple homogeneous masses, receives an 

 easy explanation on the assumption of their consisting of 

 more minute atoms. The greater brightness of the line F 

 would be accounted for by supposing the atoms, whose 

 vibrations generate this wave, to be more numerous than 

 any of the others. Those which generate the wave c would 

 be next in number; then those which generate the wave 

 near G ; lastly, those which generate the wave near H. The 

 rapidity with which the two last sets of atoms vibrate 

 would explain their requiring a greater amount of applied 



