Personal Identification and Description 



187 



and ring fingers; R. hand, thumb and little finger; and finally L. hand, thumb 

 and little finger. Thus Galton's own index formula (see his prints on our 

 p. 138) is wlw, oil, wl, vol. He indexes 100 individuals in this manner. On the 

 basis of 500 sets of digits he gives the frequency per cent, of all index-headings 

 which occur more often than l°/ - The worst of these is oil, oil, 11, 11, which 

 occurs in 4°/ of occurrences. Thus, if we were dealing with 100,000 cases, 

 we might have to search among 4000 individuals with this index-heading. 

 The rapid fall in the number of entries having only a single individual is 

 evidenced by the following returns which Gal ton gives on his p. 141 : 



When we come therefore to indices which embrace 50,000 to 100,000 

 individuals, it will be seen that it may be needful to go through a large 

 number of the cards on the o, i, a, I, w system of indexing before we identify 

 a given individual. Thus even with the use of inner and outer loops on the 

 forefingers, the great frequency of loops renders this system cumbersome for 

 large finger-print collections. I do not think that Galton in 1892, although he 

 suggests (p. 145) counting approximately the ridges, saw his way clearly out 

 of this difficulty of loop redundancy. Possibly he did not fully realise the 

 difference between his small collections and those of a national index of 

 criminals. 



In this chapter Galton describes the form of card he used for printing 

 and his manner of storing such cards (p. 145). 



Chapter X is entitled Personal Identification. This chapter contains 

 much of general interest, which, however, we can only afford space to sum- 

 marise briefly here. After referring to the ease with which any printer 

 could take finger-impressions Galton again emphasises the suitability of the 

 photographer for this work (see our p. 155), as not only can he easily enlarge 

 prints, but he keeps an index to his negatives. Galton then passes to the 

 many purposes for which identification is not only desirable but necessary. 

 He cites some very interesting remarks (pp. 150-152) of Major Ferris, of the 

 Indian Staff Corps, who, ignorant of Herschel's work, had found the same 

 series of difficulties in identification and who had seen with much appreciation 

 the finger-print method of identification at work in Galton's Laboratory — 

 even as Sir E. It. Henry did later. 



In the next place Galton gives on the whole a favourable account of 

 bertillonage (pp. 154-158), questioning, however, the statements made as to 

 the independence of the characters measured ; Bertillon had asserted without 

 demonstrating this independence. Galton shows from data of a similar kind 

 drawn from his own Anthropometric Laboratory that such variables are not 

 independent. Starting with five characters, head length, head breadth, span, 

 sitting height, and middle-finger length, he shows that 167 out of 500 persons 



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