1885.] ^^^ [Taylor. 



forms may be represented with an accuracy difficult to attain by any other 

 means. The experiments in this department of pliotography were origi- 

 nated by Francis Gallon, F.R.S., to illustrate pathological inquiry; and 

 they have excited great interest, especially among biologists, wherever 

 they have been introduced. Dr. Billings of the Army Museum at Wash- 

 ington is doing excellent work, by this means, in photographing types of 

 crania. Prof. Pumpelly of Newport, R. I., is experimenting with living 

 heads. Our townsman, Mr. W. R. Furness, in connection with a certain 

 historical research, was the first in this city, I believe, to apply this pro- 

 cess. Besides these named I know of no others in cur country working up 

 this problem. 



By the method brought before you to-night, the objects to be combined 

 are first photographed to one size and the unmounted prints are fitted one 

 over another — eyes to eyes and mouth to mouth. In order to make this 

 adjustment accurately, alight open frame, perforated at each corner with 

 a small hole, is made to fit on a block having corresponding pins on its 

 corners. The frame bears cross threads agreeing with the lines of the 

 eyes and mouth of the picture and with the average distances apart of the 

 eyes. This frame, apart from the block, is placed on the first print, and 

 the threads being brought into correspondence with the features named, 

 punctures are made in the print, through the holes in the frame, and the 

 print is then slid upon the pins in the block. All the prints are adjusted 

 to their place on the block in this way. They are then successively ex- 

 posed before the camera for such a proportion of time, each, as the number 

 of prints may indicate. For example, if sixty seconds were required for 

 an ordinary exposure, twelve prints would receive five seconds each. The 

 sensitized plate in the camera is thus acted on by a number of images pro- 

 ducing one compound image in which the separate characteristics of all 

 have equal representation. 



The first composition you are invited to examine is one made from pho- 

 tographs — mainly taken by ourselves last summer — of all the present 

 officers, seventeen in number, of the American Association for the Ad- 

 vancement of Science. In this one head there is an exactly equal repre- 

 sentation of the following named: 



Profs. Lesley, Cope, Newton, Hilgard, Putnam, Jas. Hall, Langley, 

 Morse, Eaton, N. H. Winchell, Wormley, Gray, Thurston, Jno. Trow- 

 bridge, Newcomb, Springer and Eddy. 



These notables, all laying their heads together, are supposed to present 

 to our gaze the typical scientific man. 



It would extend our interest could we have a sufficient number of spec- 

 ialists to make fair averages in the principal departments of science. 

 Whether these averages would reveal the nice points of difference that 

 would be demanded is a question experience must decide. We shall be 

 happy to press the inquiry. 



TROC. AMER. PHILOS. SOC. XXII. 120. 2t. PRINTED MAY 2G, I880, 



