CHAPTER IX 

 BIOMETRICS 



I.INTROD UCTION. 



THERE seems at first nothing so futile as seeking for any 

 definite order in the daily occurrences of life, be it births, 

 marriages, deaths, or the hundred and one other events 

 that make up the sum total of our social existence. Chance 

 and chaos appear here to reign supreme. And yet, 

 though we may be unable to tell who is going to be born, 

 who to be married, or who is destined to die in any given 

 year, it is a well-known fact that the proportion of births, 

 marriages, and deaths to the total population can be 

 expressed by a definite percentage for any given period, 

 and that, assuming the same conditions, this ratio varies 

 comparatively little from year to year. Prediction is 

 possible if not for the individual case, yet for the mass. 

 The science of statistics forms a recognized and most 

 important part of our study of social phenomena. 



Biometrics occupies itself, as its name signifies, with the 

 measurement of the phenomena of life. It applies to 

 biology the mathematical methods of statistics. The first 

 to treat biological problems from this point of view was 

 the famous Belgian astronomer and statistician Quetelet, 

 who, in his Letters on the Theory of Probability (1846), 

 demonstrated that variation takes place, according to the 

 well-known Laws of Probability. But to Francis Galton 

 belongs the honour of having been the pioneer of 

 this school of biology. It was he who in various papers, 



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