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. 11: 



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 F-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 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 finger- 

 prints. 



