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History of Science, a — Volume 2 by Henry Smith Williams;Edward Huntington Williams
page 113 of 293 (38%)


TORRICELLI

In the closing years of his life Galileo took into his family, as
his adopted disciple in science, a young man, Evangelista
Torricelli (1608-1647), who proved himself, during his short
lifetime, to be a worthy follower of his great master. Not only
worthy on account of his great scientific discoveries, but
grateful as well, for when he had made the great discovery that
the "suction" made by a vacuum was really nothing but air
pressure, and not suction at all, he regretted that so important
a step in science might not have been made by his great teacher,
Galileo, instead of by himself. "This generosity of Torricelli,"
says Playfair, "was, perhaps, rarer than his genius: there are
more who might have discovered the suspension of mercury in the
barometer than who would have been willing to part with the honor
of the discovery to a master or a friend."

Torricelli's discovery was made in 1643, less than two years
after the death of his master. Galileo had observed that water
will not rise in an exhausted tube, such as a pump, to a height
greater than thirty-three feet, but he was never able to offer a
satisfactory explanation of the principle. Torricelli was able to
demonstrate that the height at which the water stood depended
upon nothing but its weight as compared with the weight of air.
If this be true, it is evident that any fluid will be supported
at a definite height, according to its relative weight as
compared with air. Thus mercury, which is about thirteen times
more dense than water, should only rise to one-thirteenth the
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