[Illustration: SCHMID'S PATENT DETECTIVE CAMERA.
Patented January 2d, 1883.]
This Camera is focussed once for all by means of a ground glass
which slides in the place to be afterwards [p149] occupied by the
double dry-plate holder, for objects of various distances, and the
position of the focussing lever on top of the Camera is marked for
each distance. After this the ground glass may be entirely dispensed
with, as it is then only necessary to estimate the distance of the
object to be photographed, and move the focussing lever to the mark
corresponding to that distance, when the Camera will obviously be in
focus.
The small lens in the upper left-hand corner serves to throw the
picture on a piece of ground glass on the top of the Camera, thus
showing the position of the image on the plate. When the picture
appears in proper position on this ground glass, it is only
necessary to touch the button on the right of the Camera, and the
exposure of the plate is instantly made, its development being
afterward accomplished in the ordinary manner.
The slide is then replaced in the plate-holder, which, being
reversed, the shutter reset and the other slide drawn out,
everything is ready for the next shot.
This Camera is made to carry in the hand, and is held against the
side under the arm while exposures are made. A tripod or stand is
not required. The plate-holders are carried in a small satchel, with
a strap passing over the shoulder. The new sensitive paper film,
however, obviates the necessity of carrying more than one holder,
which will contain a band on which may be made 24 exposures, and
which is of no greater weight than one of the double holders when
filled with 2 glass plates.
This Camera is calculated to make pictures 3-1/4 by 4-1/4 inches in
size, and they are technically called quarter plate size. [p150]