:>J4 ANNUAL OF SCIENTIFIC DISCOVERY. 



only ; so that it is requisite to reject a hypothesis whose claims rest 

 solely on the greater imperfections of others proposed to account for 

 the same phenomena. As a better explanation of the phenomenon in 

 question, Mr. Vaughan teaches that the appearance is more probably 

 due to the dismemberment of a secondary or primary planet, brought 

 by the resistance to its motion in an ethereal medium into fatal prox- 

 imity of the central sphere, an exposition which, he maintains, 

 harmonizes in a very decided manner with the astonishing rapidity 

 with which temporary stars attain their maximum brilliancy, and 

 then assume a comparatively slow and gradual decline. 



Investigations respecting the necessary course of physical events 

 in the dark systems afford, the author further opines, still more im- 

 portant evidence in regard to the ethereal contents of space. Were 

 the central body composed of solid matter, or surrounded with an 

 atmosphere of oxygen, nitrogen, or carbonic acid, a development of 

 heat and light might be expected to attend -the dilapidation of one of 

 the satellites or the ultimate incorporation of its matter with the great 

 orb ; but the appearance would not correspond to that exhibited by 

 the temporary stars. 



"Admitting that a solid globe, almost as large as the sun, may be 

 rendered so highly incandescent as to shine like the star of 1572 at 

 the period of its greatest brilliancy, it would be impossible for it to 

 cool so rapidly as to become invisible in the course of seventeen 

 months. Besides this, it may be easily shown that if our earth had 

 a diameter of eighty thousand miles, with its present density and 

 superficial temperature, our atmosphere would have its density re- 

 duced a millionfold, with an elevation of six or seven miles. Thus 

 the greater mass we assign to the central body, the more narrow 

 must we regard the atmospheric region where light can be developed 

 by aerial compression ; and the less display of lustre could we expect 

 from this cause when a satellite fell from its stage of planetary exist- 

 ence. But this difficulty will disappear, when we suppose that the 

 ether of space forms for the several great celestial bodies extensive 

 atmospheres, which are rendered luminous by adequate compression, 

 or rather by the chemical action it induces, a theory which becomes 

 necessary to account for the luminosity of meteors, and the perpetual 

 brilliancy of suns." 



The various arguments in support of the idea of the existence of a 

 pervading ether, while they differ widely in detail from one another, 

 have this in common, viz., that they are based on inference alone, or, 

 as the lawyers would say, on circumstantial evidence. The value of 

 the evidence rests, consequently, on its accumulative character, not on 

 any direct fact. The danger of the evidence lies in the absence of di- 

 rect fact, and on the suspicion that some day a new and more compre- 

 hensive theory of the universe, and the forces by which it is animated, 

 may step in and undo the very foundations of our present learning. 

 Meanwhile, we are acting most judiciously in accepting, on the evi- 

 dence adduced, the hypothesis of the existence of an ethereal me- 

 dium. Many a human life has been sacrificed to justice, and many a 

 gigantic human enterprise been accepted, on evidence less clear, and 

 far less demonstrative. While, therefore, we may regret the insuf- 

 ficiency of our knowledge on this particular point, while we may 



