IN THE SOLAR SYSTEM. 



89 



Herschell The observations, the calculations, the successful result of the labors of M. 

 Valz to be put aside, because they, though living in the nineteenth century, were, in the 

 matter of ether, wedded to the doctrine of the ancients. The comet would want a skin. 

 Most justly did Bacon classify among the causes of error the Idols of the Theatre. 



Let me endeavor to draw a parallel which may shed some light upon this comctary phe- 

 nomenon. Suppose a given bulk of our atmosphere, containing a cloud, to be brought 

 from the region of the cumuli to the surface of the earth. Now a cloud like a comet has 

 no skin ; yet, does any one doubt that (neglecting the changes produced by heat) the cloud 

 would, by varying its position, be reduced in volume in the same proportion as the air in 

 which it was suspended] 



The theory of M. Valz was based upon data furnished by the observations and deduc- 

 tions of Encke, viz., the existence of a fluid in space having inertia. Being possessed of 

 inertia, it would be most unphilosophical to believe it wanting in the other properties of 

 matter, especially those of the aeriform bodies. His explanation was, in my opinion, a 

 masterpiece of reasoning. 



The three phenomena of comets I have now spoken of, and which have been by different 

 astronomers ascribed to the influence of ether, are features which are believed to charac- 

 terize comets as a class ; they constitute a rule which applies to all these bodies. 



It is true, some of the greatest lights which adorn the science of astronomy, disbelieve 

 in the connection between ether and these phenomena. This slowness to receive new 

 ideas, has characterized eminent men in all ages, and persons of the greatest learning, 

 whose efforts have been most availing, in the advancement of astronomy, have died in 

 utter unbelief in doctrines, in winch their contemporaries and immediate successors have 

 placed general and implicit credence. 



Tycho Brahe, who, during his whole life, had the benefit of the truths contained in the 

 great work of Copernicus "I)e Revolutionibus," believed in the immobility of the earth, 

 and in the daily revolution of the sun and planets round the same. 



What is more remarkable still, these views were held by the expounder of the inductive 

 philosophy * If anything coidd shake our confidence in the value of Bacon's exclusive 

 system, it is the fact, that with the truth before him, his inductive philosophy failed to 

 prevent him from believing in error. 



I shall now draw attention to two cometary phenomena which, unlike the three already 

 spoken of, are exceptional. I am not aware that any attempt to explain them has ever 

 been made; but if the ether with its circulation through the solar system exists, as it is 

 the purpose of this paper to describe, the explanation of both will be simple and satisfac- 

 tory. 



* Sec Bacon's essay " On the Ebb and Flow of the Sea." 



vol. xni. — 12 



