TRANSACTIONS OF THE SECTIONS. 97 



as two hundred years ago, or thereabouts. The invention of the thermometer, in 

 its present completo form, was largely due to Boyle ; and I find in his Memoirs 

 (London, 1772, vol. vi. p. 403) a letter that cannot fail to interest us, since it well 

 expresses the need of exact measurement that was thou felt in a particidar case, 

 where it was soon eminently well supplied, and therefore encourages hope that our 

 present needs as Anthropologists may hereafter, in some way or other, be equally 

 well satisfied. The letter is from Dr. John Beale, a great friend and correspondent 

 of Boyle, and is dated February, 1663. Tie says in it : — 



" I see by several of my own thermometers, that the glass-men are by you so well 

 instructed to make the stems in equal proportions, that if we could name some 

 degrees, ... we might by the proportions of the glass make our discourses intel- 

 ligible in mentioning what degrees of cold our greatest frosts do produce. ... If 

 we can discourse of heat aud cold in their several degrees, so as we may signify the 

 same intelligibly, ... it is more than our forefathers have taught us to do 

 hitherto." 



The principal experiments by which the mental faculties may be measured 

 require, unfortunately for us, rather costly and delicate apparatus ; and until phy- 

 siological laboratories are more numerous than at present, we can hardly expect 

 that they will be pursued by many persons. 



Let us now suppose that, by one or more of the methods I have described or alluded 

 to, we have succeeded in obtaining a group of persons resembling one another in 

 some mental quality, and that we desire to determine the external physical charac- 

 teristics and features most commonly associated with it. I have nothing new to 

 say as regards the usual anthropometric measurements ; but I wish to speak of the 

 great convenience of photographs in conveying those subtle but clearly visible pecu- 

 liarities of outline which almost elude measurement. It is strange that no use is 

 made of photography to obtain careful studies of the head and features. No single 

 view can possibly exhibit the whole of a solid, but we require for that purpose views 

 to be taken from three points at right angles to one another. Just as the architect 

 requires to know the elevation, side view, and plan of a house, so the Anthropologist 

 ought to have the full face, profile, and view of the head from above of the indi- 

 vidual whose features he is studying. 



It might be a great convenience, when numerous portraits have to be rapidly 

 and inexpensively taken for the purpose of anthropological studies, to arrange a 

 solid framework supporting three mirrors, that shall afford the views of which I 

 have been speaking, by reflexion, at the same moment that the direct picture of 

 the sitter is taken. He woidd present a three-quarter face to the camera for the 

 direct picture, one adjacent mirror would reflect his profile towards it, another on the 

 opposite side would reflect his full face, and a third sloping over him would reflect 

 the head as seen from above. All the reflected images would lie at the same 

 optical distance from the camera, and woidd therefore be on the same scale, but 

 they would be on a somewhat smaller scale than the picture taken directly. The 

 result would be an ordinary photographic picture of the sitter, surrounded by three 

 different views of his head. Scales of inches attached to the framework would 

 appear in the picture and give the means of exact measurement. 



Having obtained drawings or photographs of several persons alike in most 

 respects, but differing in minor details, what sure method is there of extracting the 

 typical characteristics from them ? I may mention a plan which had occurred both 

 to Mr. Herbert Spencer and myself, the principle of which is to superimpose opti- 

 cally the various drawings and to accept the aggregate result. Mr. Spencer sug- 

 gested to me in conversation that the drawings reduced to the same scale might be 

 traced on separate pieces of transparent paper and secured one upon another, and 

 then held between the eye and the light. I have attempted this with some success. 

 My own idea was to throw faint images of the several portraits, in succession, upon 

 the same sensitized photographic plate. I may add that it is perfectly easy to 

 superimpose optically two portraits by means of a stereoscope, and that a person 

 who is used to handle instruments will rind a common double eyeglass fitted with 



1877. 8 



