178 



Life and Letters of Francis Galton 



methods of enlarging them. In the Galtoniana we have still his special 

 ' camera for enlarging finger-prints (see our p. 215), his much enlarged series 

 of finger-prints used for fine classification (reproduced for this work, and to 

 be found in a pocket at the end of this volume) and the watchmaker's 

 glass mounted on a stand for directly examining them*. 



Chapter IV (pp. 54-63) deals with The Ridges and their Use. Galton 

 starts with the ridges of the palm of the hand, and indicates that they are 

 not very closely related to the "creases," so that the latter cannot be the 

 cause of the former. He also refers to the ridges on the soles and toes, but 

 ultimately confines his attention to those on the fingers. Here he defines 

 two important terms: first, Minutiae, which are the minute peculiarities 

 characterising an individual ridge. A ridge may divide into two or unite 

 with another (see Fig. 31, a and b), or it may divide and almost immediately 



CJi*.ra.cleri»tio Peculiarities irz Ridges. 



(ibout 8 \im.e.$ the natural Si& 6 ) 

 Fig. 31. 



reunite, enclosing a small circular or elliptic space (c); at other times it 

 may begin or end abruptly (d and e); or lastly the ridge may be so short 

 as to form a small island (f). Secondly, Patterns: whenever an interspace 

 is left between the boundaries of different systems of ridges, it is filled by a 

 small system of its own which will have some characteristic shape. This 

 shape is termed a pattern (see Figs. 20, 21 on our pp. 162, 163). The 

 descriptions of minutiae and of patterns belonging to an individual are of 

 special value for the purposes of identification. 



On the whole there is little known of the origin and use of the ridges, 

 beyond the fact that they carry the sweat pores. Nor is their origin or use 

 of much importance for the purpose of identification provided we can be 

 assured of their persistency during life. Titchener, as I have noted (p. 168), 

 made, at the suggestion of Galton, a series of experiments with the aesthesio- 

 meter, and proved that the fineness or coarseness of the ridges in different 

 persons had no effect whatever on the delicacy of their tactile discrimination. 



* This finger-print glass appears in Furse's painting of Galton; see the Frontispiece to Vol. I. 

 It is worth noting that Galton selected this piece of apparatus as the most characteristic of his 

 many activities. 



