144 Mr Waddell on a New Optical Instrument. 
The instrument is represented in Fig. 3. as resting on a sphe- 
rical hollow in a flat stand, which completely supplies the place 
of a universal joint, as the instrument can be turned in any di- 
rection, the weight of the metallic reflector and brass ball ren- 
dering it perfectly steady, even when the vertical tube is in a 
horizontal position. 
The purposes to which I have applied this instrument, are 
those of a Camera Obscura, Camera Lucida, Diagonal Mirror, 
and Compound Microscope, When used as a Camera Obscura, to 
assist in taking views from nature, or in drawing any other sub- 
ject, a micrometer, divided into squares, is placed at the field- 
bar of the instrument, and the drawing-paper being divided into 
corresponding squares of any dimensions, the objects seen in the 
field of view of the instrument, can, by a person at all practised in 
drawing, be delineated with the greatest truth, and on any required 
scale ; and as the instrument has a small magnifying power, dis- 
tant objects can be seen by any eye with the greatest distinctness. 
When used as a Camera Lucida, without the micrometer, the 
instrument is placed on its side upon an elevated stand, with trian- 
gular feet, as seen in Fig. 4., and the prism before mentioned is 
removed from the outer end of the horizontal tube, now fore- 
shortened, and pointing towards you, and placed on the end of 
the vertical tube, now also in a horizontal position, close by the 
eye-glass; and as it is open on the under side, as in the prism of 
the camera lucida, by a similar adjustment of the eye, the picture 
seen in the instrument will appear to be painted on the table 
below, and the outline of it may be drawn on paper, with the 
same precision as with that instrument ; for in both positions of 
the instrument above described, the objects seen are neither in- 
verted nor reversed, although, from its peculiar construction, 
they must necessarily be received into the instrument, from the 
observer’s left hand side. When used as a Diagonal Mirror, 
the prism that displaced the eye-aperture may be removed, and 
the aperture again fixed to the eye-piece, and the instrument 
placed in its former upright position upon the stand represented 
at Fig. 3. When any print or tinted view is properly illumi- 
nated, and placed in a position perpendicular to the axis of the 
instrument, then, by an adjustment of the sliding-tubes to the 
eye, as in a common telescope, the objects of the illuminated 
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