MEMOIR XV.] TAKING OF PORTRAITS BY PHOTOGRAPHY. 219 



cording to their own tastes. When one that is quite 

 uniform is desired, a blanket, or a cloth of a drab color, 

 properly suspended, will be found to answer very well. 

 Attention must be paid to the tint : white, reflecting too 

 much light, would solarize upon the proof before the face 

 had had time to come out, and owing to its reflecting all 

 the different rays, a blur or irradiation would appear on 

 all edges, due to chromatic aberration. It will be readily 

 understood, that if it be desired to introduce a vase, an 

 urn, or other ornament, it must not be arranged against 

 the background, but brought forward until it appears 

 perfectly distinct on the ground-glass of the camera. 



Different parts of the dress, for the same reason, re- 

 quire intervals differing considerably, to be fairly copied 

 the white parts of a costume passing on to solarization 

 before the yellow or black parts have made any decisive 

 representation. We have therefore to make use of tem- 

 porary expedients. A person dressed in a black coat 

 and open waistcoat of the same color must put on a tem- 

 porary front of a drab or flesh color, or by the time that 

 his face and the fine shadows of his woollen clothing are 

 evolved, his shirt will be solarized, and be blue or even 

 black, with a white halo around it. Where, however, 

 the white parts of the dress do not expose much surface, 

 or expose it obliquely, these precautions are not essential; 

 the white shirt collar will scarcely solarize until the face 

 is passing into the same condition. 



Precautions of the same kind are necessary in ladies' 

 dresses, which should not be selected of tints contrasting 

 strongly. 



It will now be readily understood that the whole art 

 of taking daguerreotype miniatures, consists in directing 

 an almost horizontal beam of light, through a blue-col- 

 ored medium, upon the face of the sitter, who is re- 

 tained in an unconstrained posture, by an appropriate 



