SCIOPTICON MANUAL
CHAPTER I.
THE CAMERA OBSCURA.
A picture formed by rays of light from the several
parts of an object as seen at A (Fig. 1), is called an
image ; and the cham¬
ber in which it is
formed, and from
which all light is ex¬
cluded, except what
enters a small hole
as at S, is called a
camera obscura.
This dark chamber
claims attention here
because its properties, which are common to the eye,
the Sciopticon, and all forms of the camera, are seen on
a broad scale, and may be readily verified by inexpensive
experiments. To avoid confusion the pencils of light
are represented in Fig. 1 without marginal rays need¬
ing to be focused by a convex lens. Explaining the fol¬
lowing properties in connection with a diagram without
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