FOR TAKING PORTRAITS. 143 



open waistcoat of the same colour, must put on a temporary front of a drab or flesh- 

 colour, 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 ex- 

 pose it obliquely, these precautions are not essential; the white shirt collar will scarce- 

 ly solarize until the face is passing into the same condition. 



561. Precautions of the same kind are necessary in ladies' dresses, which should not 

 be selected of tints contrasting strongly. 



562. 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- 

 oured medium, upon the face of the sitter, who is retained in an unconstrained posture 

 by an appropriate but simple mechanism, at such a distance from the background, or 

 so arranged with respect to the camera, that his shadow shall not be copied as a part 

 of his body ; the aperture of the camera should be three and a half or four inches at 

 least ; indeed, the larger the better, if the object glass be aplanatic. 



563. If two mirrors be made use of, the time actually occupied by the camera oper- 

 ation varies from forty seconds to two minutes, according to the intensity of the light. 

 If only one mirror is employed, the time is about one fourth shorter. In the direct 

 sunshine, and out in the open air, the time varies from under half a minute. 



564. Looking-glasses which are used to direct the solar rays, after a short time 

 undergo a serious deterioration ; the foil assuming a dull granular aspect, and losing its 

 black brilliancy. Hence the time in copying becomes gradually prolonged. 



565. The arrangement of the camera, above indicated, gives reversed pictures, 

 the right and left sides changing places. Mr. WOOLCOTT, an ingenious mechanician 

 of this city, has taken out a patent for the use of an elliptical mirror for portraiture ; 

 it is about seven inches in aperture, and allows him to work conveniently with plates 

 two inches square. The concave mirror possesses this capital advantage over the 

 convex lens, that the proof is given in its right position, that is to say, not reversed ; 

 but it has the serious inconveniences of limiting the size of the plate, and representing 

 parts that are at all distant from the centre in a very confused manner. With the lens, 

 plates might be worked a foot square, or even larger. 



566. Miniatures procured in the manner here laid down are in most cases striking 

 likenesses, though not in all. They give, of course, all the individual peculiarities a 

 mole, a freckle, a wart. Owing to the circumstance that yellow and yellowish browns 

 are long before they impress the substance of the Daguerreotype, persons whose faces 

 are freckled all over give rise to the most ludicrous results, a white mottled with just as 

 many black dots as the sitter had yellow ones. The eye appears beautifully ; the iris 

 with sharpness, and the white dot of light upon it, with such strength and so much of 

 reality and life, as to surprise those who have never before seen it. Many are per- 

 suaded that the pencil of the painter has been secretly employed to give this finishing 

 touch. 



