JULY — SEPT. 1857.] Portraits with a cotnmon Camera. 255 
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changed the right one becoming the left 
and vicepersd. Whilst for glass positives 
it is necessary to use separate glasses, the 
frame having a smaller central support as 
below. As the centre of the lenses in taking 
Stereoscopic pictures is a little above the 
centre of the Camera, the position of the 
glass plate must be made to correspond. 
I do not observe that the glasses being 
parallel instead of converging towards 
the object makes any perceptible 
difference in the pictures, but 
when a table is used to support 
the Camera, such convergence 
might be easily given by having 
a pivot under the front of the Ca- 
mera and limiting its lateral motion 
by screws placed as in the accom- 
panying figure F. 
rivot. 
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I have found it impossible to 
get made here the rather com- 
plicated exposing frame usually 
described in books on taking 
Stereoscope pictures, when a 
system of parallel bars is used 
on a table to shift the Camera 
and at the same time to move 
the coUodionized plate. With a 
Camera constructed as above the 
parallel frame might be used 
with advantage for groups of fi- 
gures and distant objects, moving 
SS two snipe shot which allow it to 
move easily. 
the object glass in a direction contrary to that given to the Ca- 
mera, when the pictures would be in their correct places on the 
glass. I send enclosed a picture or two which will show that 
