52 FROM NEBULA TO NEBULA 



Third. Let me ask, How long ago did this pro- 

 cess of tumbling-in begin? Suppose we say, to be lenient, 

 ten million years, when the sun's mass must have oc- 

 cupied, according to theory, a space equal to thrice 

 his present diameter, or, what is the same thing, twenty- 

 seven times his present volume. His heat at that time, 

 then, must have been vastly more intense than at pres- 

 ent, not only because Helmholtz says so, but also be- 

 cause, according to Boyle's law, pressure remaining 

 the same, the temperature decreases directly as the 

 volume. In other* words, the farther back we go on 

 this line the hotter and hotter our sun, precisely con- 

 tradicting the Kinetic theory, which teaches increase 

 of heat by condensation! Which of these theories is 

 right? 



According to Lane's theory, the more a gaseous 

 body contracts under its own gravity as the result 

 of cooling by radiation, the hotter it becomes ! Of course 

 he could not prove this experimentally, but only by 

 theory. Let me answer it by a corollary reductio ad 

 dbsurdum : To cool a gaseous body which is contract- 

 ing under its own gravity, heat it, for the added heat 

 will expand and thus cool it! Helmholtz's theory of 

 a sun tumbling in upon itself because it is growing cold 

 presupposes a hotter ancient sun, Lane*s a colder. In 

 either case the implied variation of the solar heat, 

 primevally from now, is geologically and biologically 

 abhorrent. Regularity, at least approximate regularity, 

 of the solar temperature is indispensable to the satis- 

 factory explanation of the earth's geological records. 



I submit, therefore, that the Kinetic Theory of solar, 

 and planetary heat, as currently misunderstood and ap- 

 plied, is fatally defective in the following vital respects : 



