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copying pictures, by dividing them into Squares with pencil 
lines, as also the paper on which the copy is to be taken? 
and then, by the eye , copying whatever is seen in each 
square of the picture on the corresponding square of his 
paper. 
As a substitute for the frame just described, and with the 
view of having something to answer the same purpose, as 
portable as could be made, I have constructed an instru¬ 
ment of the following description, which I call a DIORA- 
SCOPE, to distinguish it from one I have called a DIOR A 
GRAPH, that will be described afterwards, and which draws 
the outlines of pictures mechanically , whereas this and the 
frame, only guide the eye in making the drawing. 
Figure 15, is a representation of this instrument drawn 
In military perspective. 
THE DIORASCOPE. 
A,B,C,D, are pieces of mahogany, or other proper mate¬ 
rial, the dimensions of which may be measured by the scale. 
The limbs B and D are joined to C by hinges, so as to per¬ 
mit them to fold down towards each other, and are kept in 
an upright position by the braces E,E, which move at their 
lower ends on pins, so that they can be folded down into the 
cavities F,F. A is made in the form of a frame, divided by 
fine threads or wires into two row’s of squares, each square 
being half an inch. The inner edges of the frame are bev¬ 
elled to the middle, and perforated with holes, to receive 
the dividing threads. This piece is attached to B, by slip¬ 
ping it on two iron pins, fastened into the top of B, at 10, 
11 ; entering into corresponding holes in the low r er part of 
the frame. D is perforated along its middle, with sight 
holes, half an inch apart from each other, countersunk on 
the inner side, and numbered. G is a screw packed in its 
place, and held down at the point by a small wire staple, 
and at the other end, by one end of A, resting on it, when 
the instrument is folded up ; which is thus to be done 
Turn the braces E,E, into the cavities F,F; take off A, and 
