he
examined with a small hand-glass he himself had made. In looking at the
ray, quite accidentally, he found it could be deflected and sent off at
will in various directions. When thrown on the wall, instead of being
simply white light it had seven distinct colors beginning with violet
and running down to red. So white light was not a single element: it
was made up of various rays which had to be united in order to give us
sunlight.

Eureka! He had found the secret of the rainbow--the sun's rays broken up
and separated by the refracting agency of clouds!

Well does Darwin declare that the separation of sunlight into its
component parts, and the invention of the spectrum, have marked an
advance in man's achievement such as the world had not seen since the
time of wonder-working Archimedes.

* * * * *

The Cambridge University was closed until October, year of Sixteen
Hundred Sixty-seven. Most of the intervening time Newton spent at the
home of his mother, but from accounts of his we can see that the College
people kept their eagle-eye upon him, for they sent remittances to him
regularly for "commons."

When he returned to Cambridge he was assigned to the "spiritual
chamber," which was a room next to the chapel, that had formerly been
reserved as a guest-room for visiting dignitaries.

In March, Sixteen Hundred Sixty-eight, he was given the degree of Master
of Arts. His studies now were of a very varied kind. He was required to
give one lecture a week on any subject of his own choosing. Needless to
say his themes were all mathematical or scientific. Just what they were
can best be inferred by consulting his cashbook, since the lectures
themselves were not written out and all memoranda concerning them have
disappeared. This account-book shows that his expenditures were for a
Gunter's Book (he who invented the Gunter's Chain), a magnet and a
compass, glue, bulbs, putty, antimony, vinegar, white lead, salts of
tartar, and lenses.

And in addition there are a few interesting items such as one sees in
the Diary of George Washington: "Lost at cards, five shillings."
"Treating at tavern, ten shillings." "Binding my Bible, three
shillings." "Spent on my cousin, one pound, two." "Expenses for wetting
my degree, sixteen shillings."

The last item shows that times have changed but little: this scientist
and philosopher par excellence had to moisten his diploma at the tavern
for the benefit o