Personal Identification and Description 201
In other words, between a fifth and a quarter of the sets fall into groups which are far too unwieldy for rapid index searching. It is clear that the loops and whorls are the chief source of this trouble (see our pp. 149, 165 and 173) and Galton proceeds, to break them up by what he terms a Secondary Classification, or a system of adding subscripts to the letters of his primary classification. The subscripts or suffixes as Galton calls them are very numerous, although some can only be attached to certain patterns. For example, what would have appeared in his old (his present primary) classification as
oww, oil, WW, ii,
UWyw, ult lyy, wtyyw, fly,
where subscript y means that the core of the corresponding whorl is pear- or racquet-shaped; t denotes that there was a scar on the middle finger of the left hand; lyy denotes a loop with invasion of ridges from the side and with a racquet core; wlyy means a whorl which might be mistaken for a loop, has an invasion of ridges from the side and a racquet core, and ly denotes a loop with a like invasion only. Thus 18 symbols are used to index the set. Galton defines and discusses 28 letters and symbols which may be used as suffixes. Obviously the above system of subscripts is one liable to error either in writing or printing, and Galton, although he suggests its use, does not actually adopt it in the Directory he publishes of 300 sets of prints of the 10 digits. Here he gives the primary classification symbols on the left of his page, and then on the right in 10 columns the suffixes to be attached to each of these symbols. For example, the above formula appears as
Uwwjullj9,511-,y, -I-,t, vyllvy, -I-, vl,
where the last 10 columns correspond to the digits in order of the primary formula (9 = ww, 5 = ii, the thumb and little finger formulae of right and left hands : see our p. 198).
Besides the 28 symbols which are chiefly devoted to breaking up the large loop and whorl groups, Galton introduces for the troublesome allloops group the counting of the ridges on the forefingers. This counting he now does in a different manner from that of his earlier papers, and one which seems less liable to misinterpretation. He first determines a better line for counting the ridges on (see his pp. 78-80) than he had previously selected (see our pp. 163 and 165). The following are his rules (see Fig. 34, p. 202)
"The terminus from which the count begins is reckoned as 0; it proceeds thence up to, and including, the other terminus.
"The inner terminus lies at the top of the core of the loop, the outer terminus at the delta, but it is necessary to define their positions more exactly, as follows "Inner terminus. There are two cases
,,(a) The core of the loop may consist of an uneven number of ridges, as in each of the two figures, a' and a2; then the top of the central ridge is the inner terminus*.
I think there is a risk of confusion here to which Galton does not refer. The ridge or ridges within the "staple" may or may not meet the latter. In Figs. a' and a2 the inner ridges are made to meet the staple, and the inner terminus is not put at the top of the
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