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142 The Daguerreotype and its Applications. 
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and dried. This process, it is said, has been repeated in New 
York, and found to answer these purposes. 
The most important application of which this art was suscep- 
tibletaking portraits from life, to which it owes its chief inter- 
est—was made about the same time by Prof. Draper and by Mr. 
Wolcott, a mechanician of the city of New York. Neither pos- 
sessed any knowledge of the views of the other; and results 
similar in character were obtained by each operator, but under cir- 
cumstances differing slightly. Prof. Draper employed a Daguer- 
reotype apparatus, the lens of which was four inches in aperture; 
Mr. Wolcott substituted an elliptical mirror of seven inches aper- 
ture, in place of the lens. 
In taking Daguerreotype portraits, the camera operation should 
be concluded before the features become wearied with one mode 
of expression. Lenses of large aperture, and light as intense as 
can be borne, tempered by an interposed pane of blue glass, ate 
therefore employed to accelerate this part of the process. 
The usual arrangement of lenses consists of two French achto- 
matics, of about three inches aperture, placed a little apart in @ 
tube, the united focal length of which is eight inches. A better 
combination is said to be made by employing three of these lenses. 
The barrel in which they are mounted should project three oF 
four inches in front, to exclude the side lights from the camera. 
Reflecting mirrors are required to obtain light of sufficient in- 
tensity, on the face, in the proper direction for copying all the fea- 
tures. One, or if more convenient, two large looking glasses are 
employed. With one, the time of the camera operation is one 
fourth shorter; if two are requisite, the first reflects the ray in 
nearly vertical lines to the second, which directs it to the face. 
The mirror which directs the ray should be placed a little above 
the sitter. ‘The space about the eyes will then»be illuminated 
and a small shadow cast from the nose. 
The sitter should be brought forward from the background ; 
his head being supported steadily in an easy position, by 4 staff 
and ring at the back of his chair, and so placed, that his shadow 
shall not be copied as a part of his person. 
Two lines, one extending from the head of the sitter to the mil- 
ror, the other from the same point to the camera, should form an 
angle of about 10°. 
The camera operation is usually completed in from 1” i 
24en. ; portraits however, have been obtained in 10s. 
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