172 BULLETIN OF THE 



Nor is there known to science any natural process whereby this 

 cosmic doom may be either averted, or repaired by ulterior re- 

 versal.* And when turning backward through precessive geneses 

 of worlds and suns and systems, and recalling in imagination the 

 heat continuously expended and dissipated during millions of mil- 

 lions of years, until all matter is volatilized and re-expanded in the 

 uniform tenuity and diffusion of the primitive nebular chaos, we 

 endeavor to extend our retrograde inspection for another billion of 

 years, — lost in the dizzying retrospect, we find that we have neither 

 scale, nor mechanical principle, nor hydrodynamical theory, whereby 

 to gage or guess the antecedents of this nebular chaos. 



And here again — behind the mystery and inconceivability of 

 atomic forces, lies the still greater mystery and inconceivability of 

 primaeval nature. And yet majestic as the wondrous march of 

 cosmic evolution — (by purely human standards), it has probably 

 consumed no greater number of our fleeting years, than the revolu- 

 tions executed by the slowest atoms in a single second of time ! Or 

 by whatever number this be multiplied, how brief an interval has 

 it fulfilled in the great infinitude of panoramic time, — in the far- 

 stretching ages of a past eternity. 



While an intellectual necessity demands the continuity of causa- 

 tion and of sequence, and holds any cessation of these as positively 

 unthinkable, we thus observe that on every side we are confronted 



* Of various suggestions (made from a teleological stand-point) for re- 

 versing the great law of "dissipation," and supplying to declining systems 

 an elixir vitce for their perpetual regeneration, perhaps the two most notable 

 are those of Rankine and of Siemens. 



William J. M. Rankine, in a paper " On the Re-concentration of the 

 Mechanical Energy of the Universe," read before the British Association at 

 its Belfast meeting, in September, 1852, — assuming a boundary to the sethe- 

 rial medium, argues that the radiations dissipated outward, would at the 

 limiting surface be all reflected inward to foci, at which exhausted suns 

 would be re-kindled into incandescence, or "vaporized and resolved into 

 their elements." (Report Brit. Assoc. 1852: part II, — abstracts, p. 12. — 

 Or more fully in L. E. D. Phil. Mag. November, 1852: vol. iv, p. 358.) 



Charles William Siemens, in a paper " On the Conservation of Solar 

 Energy," read before the Ro} T al Society, March 2, 1882, assuming gaseous 

 products of combustion to be thrown off in a dissociated form from the 

 equatorial regions of the revolving sun, (as from a centrifugal fan,) argues 

 that they would be constantly indrawn at the polar regions, to be reburned 

 and again given off, — in a perpetual circulation. (Nature. March 9, 1882 : 

 vol. xxv. pp. 440-444.) 



