and its application to taking Portraits from the Life. 225 



It will now be readily understood, that the whole art of taking 

 Daguerreotype miniatures, consists in directing an almost hori- 

 zontal beam of light, through a blue coloured 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 be 

 aplanatic. 



If two mirrors be made use of, the time actually occupied 

 by the camera operation 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. 



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. 



The arrangement of the camera, above-indicated, gives re- 

 versed 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 por- 

 traiture ; 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 con- 

 vex lens, that the proof is given in its right position, that is to 

 say, not reversed* ; but it has the serious inconveniences of li- 

 miting 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. 



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 persuaded, that the pencil of the painter 

 has been secretly employed to give this finishing touch. 



Phil. Mag. S. 3. Vol. 17. No. 109. Sept. 1840. Q 



