2 8 FRANCIS GALTON 



leads naturally to eugenics, as in the ' Macmillan ' 

 paper of 1 865 . But before dealing with this I must 

 say a few words about what, in the opinion of some, 

 is Galton's chief claim to eminence — the study of 

 heredity as a whole. There is no doubt that he was 

 the first to treat thoroughly and in a strict statistical 

 method, the steps by which one generation passes 

 into the next. He was pre-eminently a lover of 

 statistics, he was indeed what Goschen called 

 himself, " a passionate statistician." 



He used Gauss's Law of Error, which Quetelet 

 had already applied to human measurements. 

 "The primary objects," he says, "of the Gaussian 

 Law of Error were exactly opposed, in one sense, 

 to those to which I applied them. They were to 

 get rid of, or to provide, a just allowance for errors. 

 But these errors or deviations were the very things 

 I wanted to preserve and to know about." 



This conception of variation impressed him 

 deeply, so that he remembered the exact spot in 

 the groiinds of Naworth Castle where it first 

 occurred to him "that the laws of heredity^ were 

 solely concerned with deviations expressed in 

 statistical units." 



What may be called the final result of Galton's 

 work in heredity is, I imagine, his ancestral law, 

 namely that "the average contribution of each 

 parent" to its offspring is one quarter, or in other 

 words, that half of the qualities of the child can be 

 accounted for when we know its father and mother. 

 In the same way the four grandparents together 



' Memories, p. 305. 



