CHAPTER XVIII 



COMPOSITE PORTRAITS AND STEREOSCOPIC MAPS 



Sir Edmund Du Cane and criminal characteristics Principle of 

 composites Analytical photography Stereoscopic photographs of 

 models of mountainous districts 



MY first idea of composite portraiture arose 

 through a request by Sir Edmund Du Cane, 

 R.E., then H.M. Inspector of Prisons, to examine 

 the photographs of criminals, in order to discover and 

 to define the types of features, if there be any, that 

 are associated with different kinds of criminality. 

 The popular ideas were known to be very inaccurate, 

 and he thought the subject worthy of scientific study. 

 I gladly offered to do what I could, and he gave me 

 full opportunities of seeing prisons and of studying a 

 large number of photographs of criminals, which were 

 of course to be used confidentially. 



At first, for obtaining pictorial averages I combined 

 pairs of portraits with a stereoscope, with more or less 

 success. Then I recollected an often observed effect 

 with magic lanthorns, when two lanthorns converge 

 on the same screen, and while the one is throwing its 

 image, the operator slowly withdraws the light from it 

 and throws it on to the next one. The first image yields 

 slowly to the second, with little sense of discordance 



in the parts that at all resemble one another. It was 



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