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200   Life and Letters of Francis Galton

of the book is to provide a method of indexing 200,000 to 300,000 individuals. Galton assumes that five anthropometric characters will each be divided into three classes as in bertillonage, and accordingly, if this provides for 3'= 243 classes, we need only to secure some method of finger .print indexing which will leave very few multiple entries in 1000 cases. This is the problem Galton sets himself; it will be seen that in 1895 he still thought it desirable to use a small dose of bertillonage to aid his index, if it was to provide rapid references to more than 1000 to 3000 individuals.

Galton here starts from the old Arch-Loop-Whorl classification with the addition of the inner and outer slope of loops on the forefinger, only now, I think unfortunately, he changes many of his symbols and some of his previous terminology. Having preferred in his earlier works "inner" for the thumb side and "outer" for the little finger side, he now adopts radial and ulnar formerly rejected; thus the symbols i and o are replaced by r and u. He still works in this index with the 10 digits arranged thus* : Right, fore, middle, ring fingers; Left, ditto. Right, thumb, little finger; Left, ditto-which in his old treatment gave 10 letters. He reduces them, however, to eight, by noting that a, 1, w can only occur pair by pair in nine ways, and he gives the first nine figures to these, so that it is possible to represent thumb and little finger prints by a single figure. Thus far it is difficult to see that much has been gained on his earlier classification. Indeed with slight changes of notation Galton's present Primary Classification is his old a, l (i, o), w system. Now the defects of this as the sole classification are well exhibited in the following table which he gives (p. 77)

Formulae with Frequencies 10 and over in 1000 Tests.

 Order of Frequency Formula Frequency of Occurrence 1 ull, ull, 11, 11 59 2 rll, rll, 11, 11 35 3 ull, rll, 11, 11 24 4 www, www, WW, ww 19 5 rll, ull, 11, 11 17 6 ulw, ull, 11, 11 14 7 ulw, ulw, ii, 11 12 8 www, www, wl, wl 11 9 wll, ull, ii, 11 10 10 ull, ull, 11, 11 10 Total 211

* He states, however (pp. 72 and 111), that he has modified this view for the purpose of indexing and now prefers to take his finger-prints in order from left little finger to right little finger. There is little doubt that the latter, the " natural " order, and also the one in which the impressions are collectively dabbed and usually rolled, is less liable to errors of reading. At the same time as it starts with the little finger it gives far less variety to the initial letters of

the index.