80 Intelligence and Miscellaneous Articles. 



occasionally note ib as astonishing. It is evident that the atoms 

 of a heated body give up vis viva to the tether : in other words, the 

 tether takes from the moving atoms of the body a part of their 

 velocity; it therefore, indeed, exerts upon them au influence which 



acts as a resistance checking their velocity, and is by no means in- 

 considerable, but of relatively great intensity. Conversely, a body 

 can receive heat not merely by contact with warmer bodies, but 

 also by radiation from without. Its atoms then take vis viva from 

 the aether ; that is, the aether imparts to the atoms an increase of 

 velocity. Consequently, in a body cooled by radiation outwards, 

 the motions of its atoms are rendered slower by the tether ; in one 

 growing warmer through radiation from without the motions of its 

 atoms are accelerated ; in a bod} r which under equal radiation out- 

 wards and inwards maintains a constant temperature the forces of 

 the aether retarding and accelerating the motions of its atoms must 

 on the whole maintain equilibrium ; and in consequence of the 

 rapid change of atom-motion into radiant heat, and of radiant-heat 

 into atom-motion, these forces must, for every temperature that 

 occurs, possess great intensity. The Icinetic theory, which takes no 

 account of such forces, is, according to the author, incapable of 

 anyhow rendering intelligible a rapid annihilation or generation of 

 atomic velocities by mere generation or annihilation of aether-undu- 

 lations, whereas to him the actinic theory, touched upon in the 

 present memoir, appears to correspond perfectly with the above 

 conclusion. According to it an essential portion of the heat of a 

 body consists of radiating heat, which is accumulated by diffusion 

 between the atoms, and, from the extreme minuteness of the mean 

 radiation-distance, is concentrated to an enormous intensity. The 

 aether, thus put into most vehement vibration, exerts at the same 

 time, upon the atoms floating in it, through the relative differences 

 of radiation (i. e. through the difference of its elasticity-forces on 

 the average existing on opposite sides of the opaque atoms irradi- 

 ating one another, and changing with their positions), proportion- 

 ally intense motive forces, by which they are alternately retarded 

 and accelerated according to their momentary positions ; and conse- 

 quently their vires vivce are to a corresponding amount expended on 

 the production of aether-undulations, by the consumption of which 

 they are again replaced. 



According to Pouillet's determination of the intensity of the 

 solar radiation, it is calculated that the mean square of the velocity 

 of the aether for direct sunlight is to that of the aether in water at 

 0° C. approximately as 1 : 273,000,000,000,000 ; and accordingly 

 it appears to the author possible that the atoms of a body recipro- 

 cally exert very intense accelerative forces (according to the hypo- 

 thesis, in the sense of attractions) by the heat-rays which they 

 emit to one another ; while the corresponding force which any 

 available source of heat exerts upon a body irradiated by it is under 

 all circumstances immeasurably little. — Kaiserliclte Alcademie der 

 WiWMSchaften in Wien, mat7iematisch-natttrwissenschaftliche Classc, 

 April 4, 1878. 



