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166   Life and Letters of Francis Galton

are not all of equal height, and occasionally will escape being inked or, even if inked, fail to be pressed on the paper. Those familiar with various types of engraving by gelatine processes will have noted like divergences when comparing pulls from the same stone under a lens. In like manner, even different copies of the same plate of Albrecht Diirer's Apocalypse woodcuts show similar variations, but no connoisseur would assert on that ground that they were not pulls from the same block. Notwithstanding this it is the minutiae which provide the best means of identifying two prints, and these are very numerous, if the finger be rolled.

The next section in Galton's memoir deals with the Persistence of Patterns (pp. 10-13) and here he had the advantage of Herschel's material. We may give a brief resume of his table on p. i i : -

 

Individual

and Plate

number

Age at

First

Print

Interval in

years before

Second Print

Total number

of minutiae

identified

1

72

9

33

2

7-1

9

36

3

Adult

28

27

4

Adult

28

36

5

Adult

28

55

6

Adult

31

27

7

Adult

30

50

8

Adult

. 31

32

Thus a total of 296 minutiae were identified.

"The upshot of a careful step by step study is that I have found an absolute and most extraordinary coincidence between the details of each of the two impressions of the same finger of the same person. There was, as the table shows, a grand total of no less than 296 (say roundly

300) points of comparison and not a single one of them failed, though I had much trouble in deciphering the ridges, especially about the V-point [inward delta] in Case 5. There was no one case found of a difference in the number of ridges between any two specified points. Never during the lapse of all these years did a new ridge arise, or an old one disappear. The pattern in all its minute details persisted unchanged, and, a fortiori, it remained unchanged in its

general character." (p. 12)Galton's method of comparing minutiae at this time was by outlining the

ridges of the two " allochronic " prints. I have arranged Galton's persistency data, outlines next prints, on our Plates VII and VIII in a manner slightly different from that of the original plates of his memoir. This outline method

has distinct advantages, if it be not here as complete as in Galton's later development elopment of it.

Galton added a line or two to the memoir on January 28, 1891, to say that he had examined a number of other pairs of impressions in the same manner, and had found only one instance of fundamental discord, .where a ridge had been partly cleft in a child, but when the child had grown to a boy the cleft had disappeared. Thus Galton, with the aid of Sir W. J. Herschel's

material, satisfactorily established for the first time the permanence of fingerprints.


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