98 



NATURE 



[May 23, 1878 



larities in the latter have disappeared and the common 

 humanity that underlies them has prevailed. Thej' repre- 

 sent, not the criminal, but the man who is liable to fall 

 into crime. All composites are better looking than their 

 components, because the averaged portrait of many persons 

 is freefrom the irregularities thatvariously blemish the looks 

 of each of them. I selected these for my first trials because 

 I happened to possess a large collection of photographs of 

 criminals through the kindness of Sir Edmund Du Cane, 

 the Director-General of Prisons, for the purpose of in- 

 vestigating criminal types. They were peculiarly adapted 

 to my present purpose, being all made of about the same 

 size and taken in much the same attitudes. It was while 

 endeavouring to elicit the principal criminal types by 

 methods of optical superimposition of the portraits, such 

 as I had frequently employed with- maps and meteoro- 

 logical traces,' that the idea of composite figures ^first 

 occurred to me. 



The other set of composites are made from pairs of 

 components. They are selected to show the extraordinary 

 facility of combining almost any two faces whose pro- 

 portions are in any way similar. 



The accompanying woodcut is as fair a representation of one of the 

 composites as is practicable in ordinary printing. It was photographi- 

 cally transferred to the wood, and the engraver has used his best 

 endeavour to translate the shades into line engraving. This composite 

 is made out of only three components, and its three-fold origin is to be 

 traced in the ears, and in the buttons to the vest. To the best of my 

 judgment the original photograph is a very exact average of its com- 

 ponents ; not one feature in it appears identical with that of any one of 

 them, but it contains a resemblance to all, and is not more like to one of 

 them than to another. However the judgment of the wood engraver is 

 different. His rendering of the composite has made it exactly like one 

 of its components, which it must be borne in mind he had never seen. 

 It is just as though an artist drawing a child had produced a portrait 

 closely resembling its deceased father, having overlooked an equally 

 strong likeness to its deceased mother, which was apparent to its rela- 

 tives. This is to me a m:)st striking proof that the composite is a true 

 combination. [I trust that the beauty of the woodcut will not be much 

 diminished by the necessarily coafse process of newspaper printing.] 



It will, I am sure, surprise most persons to see how 

 well defined these composites are. When we deal with 

 faces of the same type, the points of similarity far out- 

 number those of dissimilarity, and there is a much greater 

 resemblance between faces generally, than we who turn our 

 attention to individual differences are apt to appreciate. 

 A traveller on his first arrival among people of a race very 

 different to his own, thinks them closely alike, and a 

 Hindu has much difificulty in distinguishing one English- 

 man from another. 



' ' " Conference at the Loan Exhibition of Scientific Instruments," 1878.. 

 Chapman and Hall. Physical Geography Section, p. 312, " On Means of 

 Combining Various Data in Maps and Diagrams," by Francis Galton, F.R.S. 



The fairness with which photographic composites repre- 

 sent their components is shown by six of the specimens. 

 I wished to learn whether the order in which the compo- 

 nents were photographed made any material difference in 

 the result, so I had three of the portraits arranged 

 successively in each of their six possible combinations. 

 It will be observed that four at least of the six composites 

 are closely alike. I should say that in each of this set 

 the last of the three components was always allowed a 

 longer exposure than the second, and the second than the 

 first, but it is found better to allow an equal time to all of 

 them. 



The stereoscope, as I stated last August in my address 

 at Plymouth, affords a very easy method of optically 

 superimposing two portraits, and I have much pleasure in 

 quoting the following letter, pointing out this fact as well 

 as some other conclusions to which I also had arrived. 

 The letter was kindly forwarded to me by Mr. Darwin ; it 

 is dated last November and was written to him by Mr. 

 A. L. Austin from New Zealand, thus affording another of 

 the many curious instances of two persons being indepen- 

 dently engaged in the same novel inquiry at nearly the 

 same time, and coming to similar results. 



" Invercargill, New Zealand^ Nov. 6, 1 877. 



" To Charles Darwin, Esq. 



"Sir, — Although a perfect stranger to you, and living on 

 the reverse side of the globe, I have taken the liberty of writing 

 to you on a small discovery I have made in binocular vision in 

 the stereoscope. I find by taking two ordinary carte-de-visite 

 photos of two different persons' faces, the portraits being about 

 the same sizes and looking about the same direction, and placing 

 them in a stereoscope, the faces blend into one in a most remark- 

 able manner, producing in the case of some ladies' portraits in 

 every instance a decided improvement in beauty. The pictures 

 were not taken in a binocidar camera, and therefore do not 

 stand out well, but by moving one or both until the eyes coincide 

 in the stereoscope, the pictures blend perfectly. If taken in a 

 binocular camera for the purpose, each person being taken on 

 one half of the negative, I am sure the results would bej still 

 more striking. Perhaps something might be made of this in 

 regard to the expression of emotions in man and the lower 

 animals, &c. I have not time or opportunities to make experi- 

 ments, but it seems to me something might be made of this by 

 photographing the faces of different animals, different races of 

 mankind, &c. I think a stereo.scopic view of one of the ape 

 tribe and some low caste human face would make a very curious 

 mixture ; also in the matter of crossing of animals and the 

 resulting offspring. It seems to me something also might result 

 in photos of hu.sband and wife and children, &c. In any case 

 the results are curious if it leads to nothing else. Should this 

 come to anything you will no doubt acknowledge myself as sug- 

 gesting the experiment and perhaps send me some of the results. 

 If not likely to come to anything a reply would much oblige me. 

 " Yours very truly, 



"A. L. Austin, €.E., F.R.A.S." 



Dr. Carpenter informs me that the late Mr. Appold, 

 the mechanician, used to combine two portraits of himself, 

 under the stereoscope. The one had been taken with an 

 assumed stern expression, the other with a smile ; and 

 this combination produced a curious and effective blending 

 of the two. 



Convenient as the stereoscope is, owing to its accessi- 

 bility, for determining whether any two portraits are suit- 

 able in size and attitude to form a good composite, it is 

 nevertheless a makeshift and imperfect way of attaining 

 the required result. It cannot of itself combine two 

 images ; it can only place them so that the office of 

 attempting to combine them may be undertaken by the 

 brain. Now the two separate impressions received by 

 the brain through the stereoscope do not seem to rne to 

 be relatively constant in their vividness, but sometimes 

 the image seen by the left eye prevails over that seen by 

 the right, and vice versd. All the other instruments I 

 am about to describe accomplish that which the stereo- 

 scope fails to do ; they create true optical combina- 



