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 obviously possible to photograph superposed images on a screen by the simultaneous use of two or more lanthorns. What was common to all of the images would then appear vigorous, while individual differences would be too faint for notice. There would, however, be great difficulty in accurately superposing them without the aid of expensive apparatus. Then the idea occurred to me that no lanthorns were needed for the purpose, but that the pictures themselves might be severally adjusted in the same place, and be photographed successively on the same plate, allowing a fractional part of the total time of exposure to each portrait.

My earlier experiments were with the full-face photographs of criminals. I selected three which were not greatly unlike, and were of the same size, as judged by measuring the vertical distance between the pupils of the eyes and the parting of the lips. Out of a thin card I cut a window of the size of the portrait, and fastened two threads over it, one vertical, the other crossways. Lastly I made a pin-hole in the card on either side of the window. Thus provided, I laid each portrait in turn on the table, and adjusted the card until the cross line passed over the pupils of the eyes, and the vertical line bisected the interval. Then I pricked through the two pin-holes the paper on which the portrait was. I could thus hang all three portraits one behind the other on two pins that projected from a board, with the assurance that the principal features of each face would occupy an identical position in front of a fixed camera. I photographed them in turns. The camera was uncapped during one-third of the normal time of exposure while the first portrait was in front of it. Capping it again, I took away the front portrait and exposed the second, then uncapping the camera I took the second portrait; and similarly the third. The result was particularly promising; it was difficult to believe that the composite was not a simple portrait. I tested the truth of the result by placing the photographs in different order, and by many other ways. Then I extended its application. The method of composite portraiture was first published in _Nature_, 1878, and more fully in the _Journ. Anthrop. Inst._, 1879[51], also in the Journal of the Photographic Society, at which I exhibited it, and elsewhere. The method is republished in _Human Faculty_[76].

I gladly acknowledge my indebtedness to Sir Edmund Du Cane not only for helping me with material for these experiments, but for having, as he told me, suggested the inclusion of my finger-print system in the instructions to the Committee of Identification, described in the last chapter. He was an extremely accomplished man, with high and humane views, and sympathised with not a few of the subjects on which I have been engaged.

I have successfully made many composites both of races and of families. The composites are always more refined and ideal-looking than any one of their components, but I found that persons did not like being mixed up with their brothers and sisters in a common portrait. It seems a curious and rather silly feeling, but there can be no doubt of its existence. I see no other reason why composite portraiture should not be much employed for obtaining family types. Composites might be made of brothers and sisters, parents and grandparents, together with a composite of the race, each in their due proportions, according to the Ancestral Law (see chapter on Heredity). The result would be very instructive, but the difficulty of obtaining the material is now overwhelming. Male and female portraits blend well together, with an epicene result.

With the help of Dr. Mahomed and the permission of the authorities of Guy’s Hospital, I took many photographs of consumptive patients and made composites of them, which are published in the Guy’s Hospital Reports,