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12 O. N. Rood on producing Stereographs by Hand. 
hand; objects farther back, have their position shifted still more 
to the right hand, &e. 
This is illustrated by fig. 1, where A is in the immediate fore- 
1. ground, and D in the background. 
Now if we had a single drawing i in 
D perspective, of a house for example, 
ry and could produce a fac-simile of it, 
A this would evidently answer for the 
left-hand picture. If we could again 
reproduce this drawing on the right hand of the slide, with all 
the objects or points in it back of the immediate foreground, 
shifted to the right hand the proper distances, we should nerd a 
pair of pictures, which when combined in the stereoscope would 
give T elief, 
To oo this is the era o the machine seen in fig. 2. 
It s of a board, 10 in. by 
Ppwady 
eated in the figure: its motion is ef 
fected by the screw A, which acts 
: against the India rubber band I: the 
~ screw and its support are removable 
at pleasure. Ther mirror M serves for illumination ; the shade B 
moves on hinges, and regulates the amount of light which falls 
on the paper while the drawing i is being 
© produce a stereograph, the object or objects to be repre- 
are drawn in hs ib with ink on writing paper; this 
un 
hand has been pro educed eet is chs left-hand pict : 
The slider is now moved toward the right sand a paistensd of © 
9-6 in. and the screw with the India rubber band attached. a 
An object, or a small portion of an object, in the immedute — 
foreground is now traced, then the screw is turned slightly so as _ 
throw the next object, or the remainder of the first object, — 
slightly toward the right hand where it also is drawn, &e, Thus 
we advance slowly toward the background, turning the screw . 
