at the question as to the nature of color had commanded
the attention of such investigators as Huygens, but that no very
satisfactory solution of the question had been attained. Newton proved
by demonstrative experiments that white light is composed of the
blending of the rays of diverse colors, and that the color that we
ascribe to any object is merely due to the fact that the object in
question reflects rays of that color, absorbing the rest. That white
light is really made up of many colors blended would seem incredible
had not the experiments by which this composition is demonstrated become
familiar to every one. The experiments were absolutely novel when Newton
brought them forward, and his demonstration of the composition of light
was one of the most striking expositions ever brought to the
attention of the Royal Society. It is hardly necessary to add that,
notwithstanding the conclusive character of Newton's work, his
explanations did not for a long time meet with general acceptance.

Newton was led to his discovery by some experiments made with an
ordinary glass prism applied to a hole in the shutter of a darkened
room, the refracted rays of the sunlight being received upon the
opposite wall and forming there the familiar spectrum. "It was a very
pleasing diversion," he wrote, "to view the vivid and intense colors
produced thereby; and after a time, applying myself to consider them
very circumspectly, I became surprised to see them in varying form,
which, according to the received laws of refraction, I expected should
have been circular. They were terminated at the sides with straight
lines, but at the ends the decay of light was so gradual that it was
difficult to determine justly what was their figure, yet they seemed
semicircular.

"Comparing the length of this colored spectrum with its breadth, I found
it almost five times greater; a disproportion so extravagant that it
excited me to a more than ordinary curiosity of examining from whence it
might proceed. I could scarce think that the various thicknesses of
the glass, or the termination with shadow or darkness, could have any
influence on light to produce such an effect; yet I thought it not
amiss, first, to examine those circumstances, and so tried what would
happen by transmitting light through parts of the glass of divers
thickness, or through holes in the window of divers bigness, or by
setting the prism without so that the light might pass through it