Chase.] Oi^ [Nov. 4, 



sumed that they have affected different elements in different ways and to 

 diflerent degrees. I still think that the true value of M^ is about one per 

 cent, greater, and the value of /^^ about J of one percent, greater than here 

 given. 



"Weber and Kohlrausch demonstrated the importance of photic velocity 

 in electromotive energy, by measuring quantity of electricity ; Thomson 

 and Maxwell, by measuring electromotive force ; Ayrton and Perry, 

 by measuring electrostatic capacity. 



97. Maximum Density of Water. 



^ If we let u^ represent the potential velocity of water at its greatest den- 

 sity, we find that the greatest known velocity of sethereal wave-propaga- 

 tion : the greatest known gravitating velocity : : the corresponding circu- 

 lar-orbital velocity : the potential velocity of water at its greatest density. 



Vj^ : ®„ t/2 : : «„ : % (1) 



Let = 100^ C. — water-temperature of maximum density ; p^ = 

 Earth's semi-axis major = nr^ ; r,, = Sun's semi-diameter. Then 

 «^ =^3-4-497.827 (2) 



v„ z= n^ y<. 2 t: ps -^ 1 year in seconds (3) 



Ui=V2gh = V2gdX 1389.6 h- 5280 (4) 



If we substitute (2), (3) and (4) in (1), and adopt the British Nautical 

 Almanac estimate, n = 214.45, the most satisfactory experimental determi- 

 nations of give the following results : 



"Whatever value may be adopted for Sun's apparent semi-diameter and 

 for 0, the corresponding value for Earth's semi-axis major may be readily 



found, since ps oc v — 



'^ n 



98 . Electric Mass. 



Many of the foregoing relations seem to show that if the factor M, 

 in electric dimensions, has any proper analogy to the mass-factor in ordi- 

 nary energy, it should be referred to the particles, or the most minute ap- 



