Chase.] 57o ' [Nov. 4, 



The thallium line, 5340, is the only one which differs enough from the 

 harmonic length to throw doubt on its subjection to harmonic influence. 

 If this line were omitted altogether in the calculation, the only change 

 would be in the fourth harmonic divisor, which would be 1.0824 instead 

 of 1.0825. The harmonic wave-lengths would all remain the same as 

 above given. 



110. Mechanical Analogies. 



The researches' of Challis and Norton have shown how extensively the 

 various operations of energy may be represented and anticipated by 

 applying the laws of fluid motion. My own kinetic investigations have 

 been greatly helped by my apparatus,* for imitating the "lines of force " 

 which are represented by atmospheric, thermal and electric curi'ents. The 

 telephone, phonograph and photophone furnish practical illustrations of 

 the " mechanical polarization " for which my apparatus was devised. M. 

 C. A. Bjerknes has lately sent a communication to the French Academy 

 "sur V imitation, par la voie hydrodynamique, des actions electriques et mag- 

 netiques." As the indications of unity of force increase, there will be an 

 increased call for the study of such analogies with the help of mechanical 

 contrivances. 



111. Subsident and Paramttral Nodes. 



If we take Sun's semi-diameter, Laplace's limit and Earth's nascent 

 locusf as the elements of the stellar-solar paraboloid, we find 

 :^2_2p|r = . 9958534 

 ^ ==.1666667 

 2p = 5.950343 

 The product of the parameter by any paraboloidal abscissa represents the 

 corresponding ordinal vis viva, and the laws of harmonic undulation in 

 elastic media lead us to look for nodes in accordance with the living force. 

 We find numerous evidences of such accordance in the primitive cometoid 

 nebula, if we suppose the nucleal tendencies in the axis of abscissas to be 



* For description see Proc. Amer. Phil. Soc, x, 151-66. 

 t Note 46, ante, xix, 446. 



