194 F. W. Very— A Cosmic Cycle. 



reminds ns that the ether is a very peculiar substance, and that 

 its properties are such as would be considered unconscionably 

 exaggerated, if stated of ordinary matter. Consequently we 

 are not doing violence to known facts by giving extraordinary 

 properties to ether, nor by predicting that the change from 

 ether to matter, or the reverse, must involve the disappearance 

 or reappearance of an enormous amount of energy. It appears, 

 therefore, not improbable that the destruction or simplification 

 of material atoms is capable of setting free the forces which 

 are required for stellar disruption. If the ether has a capacity 

 for absorbing enormous energy in becoming converted into 

 atoms, then this energy is set free when the atoms are 

 destroyed, and the duration of the sun is thereby prolonged. 



The remaining links in the argument are surmises, or are 

 necessary to the completion of the cycle. Their justification 

 is the conviction that there must be a cycle of some sort ; that 

 if we find water flowing continually down hill, there must be 

 some process by which it gets to the top again. The sugges- 

 tions are made more as questions for solution than as answers. 

 But I may be permitted to point out that the present attempt 

 at an answer to the question : How does the sun maintain its 

 heat, and how long may the sun endure? reconciles several 

 dilemmas. 



Solar Sustentation. 



The logical necessity for some kind of cycle in the relation 

 of the sun to surrounding space was doubtless the foundation 

 of Siemen's attempt to devise a working theory in which the 

 sun was regarded as a kind of ventilating fan, drawing in fuel 

 from a universal gaseous atmosphere of elementary composi- 

 tion, and casting it off as burned matter to be dissociated by 

 radiation. The hypothesis has been so completely demolished 

 by Hirn and others that it is unnecessary to refer to it any 

 further than to say that it is entirely inadequate, if for no other 

 reason, because the employment of the solar rotation as a 

 motive power must destroy the rotation, and thus the entire 

 scheme in a comparatively short time. But the shortness of 

 the available time of the sun's present radiant power is also a 

 serious difficulty which must be urged against the contraction 

 theory, because the duration of the earth, since it has been 

 cool enough to sustain life, is necessarily shorter than that of 

 the sun, and yet it outspans the probable term of solar exist- 

 ence. 



Professor See* finds that the past duration of solar radiation 

 at the present rate, for which Helmholtz obtained a value of 

 18,000,000 years by the contraction theory, assuming a homo- 



* T. J. J. See, Astronomische Nachrichten, vol. cl, p. 177, 1899. 



