When the sunlight strikes raindrops in the air, they act like a prism
and
form a rainbow. The rainbow is a division of white light into many
beautiful colors. These take the shape of a long round arch, with its
path high above , and its two ends apparently beyond the horizon.
There is, according to legend, a boiling pot of gold at one end. People
look, but no one ever finds it. When a man looks for something
beyond his reach, his friends say he is looking for the pot of gold
at
the end of the rainbow.
Throughout the centuries men have explained the rainbow in various
ways. Some have accepted it as a miracle without physical explanation.
To the Hebrews it was a token that there would be no more universal
floods. The Greeks used to imagine that it was a sign from the gods
to
fortell war or heavy rain. The Norsemen considered the rainbow as a
bridge over which the gods passed from earth to their home in the sky.
Other men have tried to explain the phenomenon physically. Aristotle
thought that the rainbow was caused by reflections of the sun's rays
by the rain. Since then physicists have found that it is not reflection,
but
refraction by the raindrops which causes the rainbow. Many
complicated ideas about the rainbow have been formed. The
difference in the rainbow depends considerably upon the size of the
water drops, and the width of the colored band increases as the size,
of the drops increases. The actual primary rainbow observed is said
to be the effect of superpositioning of a number of bows. If the red
of
the second bow falls upon the green of the first, the result is to
give a
bow with an abnormally wide yellow band, since red and green lights
when mixed form yellow. This is a very common type of bow, one