had been kept
properly ignorant of such poverty-stricken subjects, and to study
medicine he went.

But his natural bent showed itself even here. For praying one day in the
cathedral, like a good Catholic as he was all his life, his attention
was arrested by the great lamp which, after lighting it, the verger had
left swinging to and fro. Galileo proceeded to time its swings by the
only watch he possessed--viz., his own pulse. He noticed that the time
of swing remained, as near as he could tell, the same, notwithstanding
the fact that the swings were getting smaller and smaller.

By subsequent experiment he verified the law, and the isochronism of the
pendulum was discovered. An immensely important practical discovery
this, for upon it all modern clocks are based; and Huyghens soon applied
it to the astronomical clock, which up to that time had been a crude and
quite untrustworthy instrument.

The best clock which Tycho Brahe could get for his observatory was
inferior to one that may now be purchased for a few shillings; and this
change is owing to the discovery of the pendulum by Galileo. Not that he
applied it to clocks; he was not thinking of astronomy, he was thinking
of medicine, and wanted to count people's pulses. The pendulum served;
and "pulsilogies," as they were called, were thus introduced to and used
by medical practitioners.

The Tuscan court came to Pisa for the summer months--for it was then a
seaside place--and among the suite was Ostillio Ricci, a distinguished
mathematician and old friend of the Galileo family. The youth visited
him, and one day, it is said, heard a lesson in Euclid being given by
Ricci to the pages while he stood outside the door entranced. Anyhow, he
implored Ricci to help him into some knowledge of mathematics, and the
old man willingly consented. So he mastered Euclid, and passed on to
Archimedes, for whom he acquired a great veneration.

His father soon heard of this obnoxious proclivity, and did what he
could to divert him back to medicine again. But it was no use.
Underneath his Galen and Hippocrates were secreted copies of Euclid and
Archimedes, to be studied at every available opportunity. Old Vincenzo
perceived the bent of genius to be too strong for him, and at last gave
way. With prodigious rapidity the released philosopher now assimilated
the elements of mathematics and physics, and at twenty-six we find him
appointed for three years to the university chair of mathema