ON AMHROrOMETRIC INVESTIGATION IN THE ISRITISH ISLES. 381 



pleting the first series of photographs; unless, indeed, there happen to be 

 two operators, each with his own camera, ready to take the same persons 

 in turn. 



2. If the camera has a stand with vertical rack-and-pinion adjustment, 

 the subject's place should be fixed, and the camera should be raised and 

 lowered to suit each subject. A square of the standard size of the picture 

 should he ruled on the focussing screen of the camera. 



3. For field work, and wherever the camera has no such adjustable 

 stand, the camera should be set at a fixed height and all the subjects 

 should occupy in turn the same chair, with movable blocks of known 

 thicknesses on the seat to raise the heads of successive sitters to a uniform 

 height. It is, however, tedious and clumsy to adjust each sitter's height 

 by trial in front of the camera. The simpler plan is to make the sitter 

 first take his place on a separate seat with his back to a wall, on which 

 are previously marked, at heights corresponding to those of the various 

 heights of head, the numbers of the blocks that should be used in each 

 case The appropriate number for the sitter is found and noted, and 

 then the proper blocks are placed on the chair by the observer or an 

 assistant, with the assurance that what is wanted has been correctly 

 done. 



4. The position of the sitter is easily controlled by the operator if he 

 looks at the sitter's head over the middle line of the camera, against a 

 mark on the background. 



The subject can also be caused to afijuot himself approximately by 

 means of sights arranged on the side of the camera, as follows : — 



^ is a small mirror with a cross + painted on it. It is set at an 

 angle of 45° to the sitter's line of sight. 



DiAQEAlI A. 



Diagram B. 



^ 



y\ 



^ is a pin with head of glass or polished metal. The sitter is told to 

 keep the head of the pin sighted in the intersection of the cross. 



The sams device m^y be employed in photographing side-face to keep 

 the sitter in the right focal plane. In this case the sights are set up in 

 the focil plane, facing the sitter. Or a small plain niiti-or (C) may be 

 hung up, so that the sitter can only .see his face in it when he is in the 

 tight pose and focal plane. 



