F. W. Very— A Cosmic Cycle. Ill 



general agreement with the fundamental principle that explo- 

 sions are prime factors in cosmic development. 



After each separation of a planet by combined explosive and 

 centrifugal force, the solar rotation is reduced until gradually 

 restored by contraction of the cooling sun, when the process 

 may be repeated. If in addition there is a gradual destruction 

 of the solar substance, there is another factor producing reces- 

 sion, and one which acts at every distance. If this destruction 

 of matter has continued throughout the solar history, and if 

 the earliest planets have endured proportionately longer and 

 have been proportionately more subjected to the resultant 

 change of distance, these will depart most widely from an 

 equable distribution, depending upon the alternation of periods 

 of increasing rotary velocity due tu contraction, and sudden 

 slowing of rotation by explosive overthrow ; and the oldest 

 planets must have proportionately greater distances. In this 

 way the departures from Bode's law may perhaps be explained, 

 the law itself being an expression of the relation between con- 

 traction of the superficially cooling sphere, increasing angular 

 velocity, and explosive epochs depending on the attainment of 

 a critical stage of partial release from equatorial pressure by 

 centrifugal force. 



It has been generally recognized that some other origin of a 

 nova then that of intersecting meteor streams may be found. 

 In the light of the evidence of cosmic explosions which has 

 now been accumulated, I wish to suggest that in the novae we 

 have the very thing sought — the actual disruption of a star by 

 a tremendous central explosion, and the dissipation of its sub- 

 stance in a great cloud of gas and meteoric dust. This partly 

 reverses Lockyer's hypothesis. The meteor-swarm is subsequent 

 instead of immediately antecedent to the nova. An explosion 

 of such gigantic magnitude cannot be absolutely instantaneous. 

 Initial velocities approaching 1000 kilometers per second are 

 recorded. Thus JVova Aurigae exhibited a velocity of 800 

 kilometers per second in February 1892. After the revival of 

 luminosity in August 1892, a velocity of — 225 kilometers per 

 second was measured, and in August 1893, this had diminished 

 to — 71 kilometers per second. The gaseous streams must 

 have reached three times the distance of Neptune in a year and 

 a half. It is possible that a measure of the radius of the 

 resultant planetary nebula may some time give us the distance 

 of a nova.* 



All of the novae show the same general sequence of 

 phenomena. The sudden release of superheated interior sub- 



* Since this was written (April, 1901), the formation of a nebula of considerable 

 size and rich in structure around Nova Persei 1901 has lent new interest to this 

 suggestion. 



