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HOW A CAST SHADOW CAN NEVER BE OF THE SAME SIZE AS THE BODY
THAT
CASTS IT.
If the rays of light proceed, as experience shows, from a single
point and are diffused in a sphere round this point, radiating and
dispersed through the air, the farther they spread the wider they
must spread; and an object placed between the light and a wall is
always imaged larger in its shadow, because the rays that strike it
[Footnote: 7. The following lines are wanting to complete the
logical connection.] would, by the time they have reached the wall,
have become larger.
1
65.
Any shadow cast by a body in light and shade is of the same nature
and character as that which is inseparable from the body. The centre
of the length of a shadow always corresponds to that of the luminous
body [Footnote 6: This second statement of the same idea as in the
former sentence, but in different words, does not, in the original,
come next to the foregoing; sections 172 and 127 are placed between
them.]. It is inevitable that every shadow must have its centre in a
line with the centre of the light.
On the shape of derived shadows (166-174).
136
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