Chase.] ^« 4 [jan. 19, 



A. P. S., xiii, 151), I sliowecl the accordance between the wave length of 

 the principal Frauenhofer lines and of the homonymous notes of the 

 twenty-third musical octave, the greatest difiference being 2| per cent., and 

 the closest approximation being at F, where the difference is less than f ot 

 one per cent. In the arithmetical mean, the difference is less than i of one 

 per cent. ; in the geometrical mean the accordance is exact. Langley, in 

 a communication to the British Association, at Southampton, reported 

 experiments which show a fundamental solar "tint which must approxi- 

 mately represent that at the photosphere, and which is most similiar to 

 that of a hue near Fraueuhofer's F." {Am. Jour. Sci., Nov. 1882). See 

 also Notes 41, 42, 235. 



320. Limit of Thermal Velocity. 



In Notes 58, 61, 62 and 102 I introduced some thermodj'namic consider- 

 ations Avhich were based on interstellar photodynamic influence. In April 

 1865, {Proc. A. P. 8., x, 101) I called attention to the fact that "even 

 the thermal currents are occasioned simply and solely by the varying 

 gravitation of fluids of varying density," and in nearly all my physical 

 papers I have been guided by the belief that all ultimate energy is radiant 

 from or toward kinetic centres, the various forms, (luminous, thermal, 

 electric, gravitating, etc.) being merely due to subordinate modifications 

 of primitive radiations. The simultaneous radiation of light and heat 

 from the Sun, the " Thomson Effect" (see Am. Jour. Sci., xxiv, 379-87), 

 and the phenomena of thermo-electricity, furnish strong a priori grounds 

 for believing that the limit ot thermal velocity, Vq, is the same as the limit 

 of luminous velocity, v^. 



321. Extension of Fundamental Equality. 



In throwing a ball into the air, the thermal equivalent of the projectile 

 force is equal to the product of the mass by the sum of the retardations 

 which result from gravitating influence, atmospheric resistance and all 

 other opposing circumstances. In solar rotation, all the solar supei'ficial 

 particles are alternately projected from and drawn towards the chief 

 centre of gravity of the system, in cyclical periods of half-rotation. The 

 thermal equivalent of this projection represents the whole work of gravity 



for the time, ^^- , and the corresponding velocity, Vg, is equivalent to the 

 2 



velocity of light. This gives the following extension of the equation in 



Note 280: 



The combination of centripetal and centrifugal tendencies which produces 

 solenoidal terrestrial currents (Note 274), may, perhaps, suggest consider- 

 ations which will be serviceable in general electrical research, and so lead 

 to important developments of this fundamental equation. 



