346 Mr. Francis Galton [May 25, 



WEEKLY EVENING MEETING, 



Friday, May 25, 1888. 



John Eae, M.D. LL.D. F.E.S. Vice-President, in the Chair. 



EfiAxcis Galton, Esq. M.A. F.E.S. M.H.I. 



Personal Identification and Description * 



It is strange that we should not have acquired more power of de- 

 scribing form and personal features than we actually possess. For 

 my own part I have frequently chafed under the sense of inability to 

 verbally explain hereditary resemblances and types of features, and 

 to describe irregular outlines of many different kinils, which I will 

 not now particularise. At last I tried to relieve myself as far as 

 might be from this embarrassment, and took considerable trouble, and 

 made many experiments. The net result is that while there appear 

 to be many ways of approximately effecting what is wanted, it is 

 difficult as yet to select the best of them with enough assurance to 

 justify a plunge into a rather serious undertaking. According to the 

 French proverb, the better has thus far proved an enemy to the pass- 

 ably good, so I cannot go much into detail 

 -p , at present, but will chiefly dwell on general 



' principles. 



/^^^^^^\ Measure of Besemhlance. — We recognise 



/<f |\ different degrees of likeness and unlikeness, 



//^ )i}\ though I am not aware that attempts have as 



IJ^ A(/,' )B ygt \)eeii made to measure them. This can 



It U/ be done if we take for our unit the least 



3 jj discernible difference. The application of this 



I y^J principle to irregular contours is partica- 



I /^ / larly easy. Fig. 1 shows two such contours, 



^^..,^^^-^^^^ A and B, which might be meteorological, 



^ — ""^ geogi-aphical, or anything else. They are 



drawn with firm lines, but of different 

 strengths for the sake of distinction. They contain the same area, 

 and are so superimposed as to lie as fairly one over the other as may 

 be. Now draw a broken contour which we will call C, equally sub- 

 dividing the intervals between A and B ; then C will be more like A 

 than B was. Again draw a dotted contour, D, equally subdividing 

 the intervals between C and A ; the likeness of D to A will be again 



♦ The substance of the lecture \a, here reprinted from ' Nature ' of June 21 

 and 28, with the kind permission of the Editor, and after some slight revision 

 by the author. 



