instance, in acquiring the sensation of redness our eyes are affected
482 millions of millions of times; of yellowness, 542 millions of
millions of times; and of violet, 707 millions of millions of times
per second. Do not such things sound more like the ravings of madmen,
than the sober conclusions of people in their waking senses? They are,
nevertheless, conclusions to which any one may most certainly arrive,
who will only be at the trouble of examining the chain of reasoning by
which they have been obtained.


_Extraordinary Property of Shadows_.

An eminent living geometer had proved by calculations, founded on strict
optical principles, that in the _centre of the shadow_ of a small
circular plate of metal, exposed in a dark room to a beam of light
emanating from a _very small brilliant point_, there ought to be no
darkness,--in fact, _no shadow_ at that place; but, on the contrary,
a degree of illumination precisely as bright as if the metal plate were
away. Strange and even impossible as this conclusion may seem, it has
been put to the trial, and found perfectly correct.

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THE NATURALIST.

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