COINCIDENCES AND SUPERSTITIONS. 391 



found, Schiaparelli's case was made out. If not, then, 

 though the evidence might be convincing to mathema- 

 ticians well grounded in the theory of probabilities, 

 yet it was all but certain that Schiaparelli's theory 

 would presently sink into oblivion. Now there are 

 probably hundreds of comets which have a period of 

 thirty-three and a quarter years, but very few are 

 known only three certainly and one of these had 

 only just been discovered when Adams' results were 

 announced. The odds were enormous against the 

 required cornet being known, and yet greater against 

 its having been so well watched that its true path had 

 been ascertained. Yet the comet which had been dis- 

 covered in that very year 1866 the comet called 

 Tempel's, or I. 1866 was the very comet required to 

 establish Schiaparelli's theory. There was the path of 

 the meteors assigned by Adams, and the path of the 

 comet had been already calculated by Tempel before 

 Adams' result had been announced ; and these two 

 paths were found to be to all intents and purposes 

 (with an accuracy far exceeding indeed the require- 

 ments of the case) identical. 



To the remarkable coincidences here noted, coin- 

 cidences rendered so much the more remarkable by 

 the fact that the August comet is now known to return 

 only twice in three centuries, while the November 

 comet returns only thrice per century, may be added 

 these : 



The comet of 1862 was observed, telescopically, by 

 Sir John Herschel under remarkably favourable circum- 



