&amp;gt;f 



CHAPTER II. 



FURTHER DISCUSSION UPON THE NATURE OF THE SERIES 

 MENTIONED IN THE LAST CHAPTER. 



1. IN the course of the last chapter the nature of a par 

 ticular kind of series, that namely, which must be considered 

 to constitute the basis of the science of Probability, has re 

 ceived a sufficiently general explanation for the preliminary 

 purpose of introduction. One might indeed say more than 

 this ; for the characteristics which were there pointed out are 

 really sufficient in themselves to give a fair general idea of 

 the nature of Probability, and of the sort of problems with 

 which it deals. But in the concluding paragraphs an indi 

 cation was given that the series of this kind, as they actu 

 ally occur in nature or as the results of more or less artificial 

 production, are seldom or never found to occur in such a 

 simple form as might possibly be expected from what had 

 previously been said ; but that they are almost always seen 

 to be associated together in groups after a somewhat com 

 plicated fashion. A fuller discussion of this topic must now 

 be undertaken. 



We will take for examination an instance of a kind with 

 which the investigations of Quetelet will have served to 

 familiarize some readers. Suppose that we measure the 

 heights of a great many adult men in any town or country. 

 These heights will of course lie between certain extremes in 



