220 ANNUAL KEPOBT SMITHSONIAN INSTITUTION, 1913. 



The absolute validity of the principle of the conservation of 

 energj^ is incontestable, but its new differential form ^ leads in 

 entirely new directions. The cause of the indefinite constancy of 

 the temperature of the sun rises from the inevitable reaction of the 

 differential law of gravitation on the law of the propagation or 

 radiation of energy and in particular the differential law of the 

 conduction of heat, established by Fourier. The forms of the two 

 differential laws must be placed in opposition to each other in order, 

 when taken together, to correspond to the principle of energy. The 

 very considerable role which the mass of bodies plays as the cause 

 of the concentration of the forces of gravitation demands a corre- 

 sponding influence of the mass of bodies on the concentration of 

 energy. To the radiation of energy called the flow of heat there 

 corresponds a new flow of energy in the direction of gravitation. 

 Thus the law of the conduction of heat established by Fourier is 

 strictlj^ applicable only to media of extremely slight density. In 

 dense substances there must be a hitherto unrecognized concentration 

 of energy, and this is not an hypothesis, but simply the balance of 

 the system of laws of effects from point to point. All dense bodies 

 should in consequence produce heat incessantly and spontaneously. 

 All bodies are so many radiators functioning without loss, although 

 in very different and to us generally imperceptible degrees. Far 

 from being in contradiction to the principle of energj^, this fact 

 springs exactly from its expression in the form of the law of effect 

 from point to point. The salts of radium, indeed, produce a similar 

 effect of spontaneous radiation, but this is of such an exceptional 

 intensity that it has amazed the physicists. Upon its discovery 

 doubts were conceived of the validity of the principle of energy, 

 but it is only the integral form of the principle which gives place 

 to these doubts, while the differential form, or the law of effect 

 from point to point, is thus all the more firmly established. The 

 increase of temperature in the deep strata of the earth is explained 

 by this effect of spontaneous radiation without the intervention of 

 the hypothesis of deposits of radium. Moreover, there is produced 

 toward the sun an enormous concentration of the new radiation of 

 energy arising from the field of gravitation, which compensates for 

 the loss of energy which the sun undergoes and assures the permanent 

 constancy of its mean temperature. Consequently the sun yields 

 no energy at all to the wide circle of cosmic space; that which it 

 radiates into cosmic space is recovered in the form of this flow of 

 energy from the field of gravitation. The senseless w'aste of the 

 sun's energy, of which the theory of effects at a distance seems to 



1 G. Jaumann, Sitziingsber. K. Akad. Wiss., Wien. Mnth.-Natnrwiss. Kl., vol. 117, pt. 

 2a, p. 388 et wq. ; vol. 120, p. 398 and p. 505 ; vol. 121, p. 169. 



