172 Life and Letters of Francis Galton
columns of figures on the left side of Fig. 27. There, the sequence of the numerals that express the patterns on the digits is divided into two groups of three numerals and two groups of two numerals, as 355, 455, 55, 35. The first group 355 refers to the first, second and third fingers of the left hand*; the second group 455 to the first, second, and third fingers of the right hand; the
,23 T4 T4
T , z 3
415 .5~5 35,55
third group 55 to the thumb and fourth finger of the left hand; the fourth group 35 to the thumb and fourth finger of the right hand. The index is arranged in the numerical sequence of these sets of numbers as shown in Fig. 27t." (pp. 542-3.)
It will be seen from Fig. 27 that Galton drew a rough symbol denoting the nature of his subclasses, the a to w of Fig. 26 in his index. The symbols with dots attached mark cases in which there may be doubt as to classification. Thus the primaries f and g may have been classed by another as loops. If there has been hesitation about them, after seeking them as loops, a second reference to the index should be made, treating them as primaries. When a whorl is "crozier" shaped, as j, k, 1, m, it lies in a loop, and may when it approaches the plain eyes t, u give rise to hesitation and a dot is then added, as at 1, m. Galton says that he has not found much difficulty with transitional cases, and considers it could be well surmounted if a standard collection of doubtful forms were established to ensure that different persons would abide by a common rule.
Galton (pp. 545-6) gives an index based on the ten finger-prints of 100 persons. In this index there are nine cases of duplicated numbers and three
* Galton's first finger = forefinger, second finger = middle finger, third finger = ring finger, and fourth finger = little finger. Galton's purpose is clear, but there are distinct and.greater advantages in the "natural ".order.
t The last column in Galton's figure, our Fig. 27, requires explanation ; it is the page reference to his records where the actual finger-prints will be found. The word "Index" at the head of the column is, perhaps, not explanatory enough.