through a small hole in a shutter, it will form a white round spot
upon the place where it falls. If a triangular prism of glass
be placed on the inside of the dark room, so that the beam
of light falls upon it, it no longer has the same direction,
nor does it form a round spot, but an oblong painted image of
seven colors--red, orange, yellow, green, blue, indigo, and violet.
This is called the solar spectrum, and will be readily understood
by reference to the accompanying diagram, Fig. 1.

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To those who are unacquainted with the theory of light
(and for their benefit this chapter is given), it may be a matter
of wonder how a beam of light can be divided.

[amdg_1.gif]

This can be understood when I say, that white light is a bundle
of colored rays united together, and when so incorporated,
they are colorless; but in passing through the prism
the bond of union is severed, and the colored rays come
out singly and separately, because each ray has a certain
amount of refracting (bending) power, peculiar to itself.
These rays always hold the same relation to each other,
as may be seen by comparing every spectrum or rainbow;
there is never any confusion or misplacement.

There are various other means of decomposing

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