discovery was of the greatest importance to a correct
understanding of the science of the motions of fluids. He also
discovered the valuable mechanical principle that if any number
of bodies be connected so that by their motion there is neither
ascent nor descent of their centre of gravity, these bodies are
in equilibrium.

Besides making these discoveries, he greatly improved the
microscope and the telescope, and invented a simple microscope
made of a globule of glass. In 1644 he published a tract on the
properties of the cycloid in which he suggested a solution of the
problem of its quadrature. As soon as this pamphlet appeared its
author was accused by Gilles Roberval (1602-1675) of having
appropriated a solution already offered by him. This led to a
long debate, during which Torricelli was seized with a fever,
from the effects of which he died, in Florence, October 25, 1647.
There is reason to believe, however, that while Roberval's
discovery was made before Torricelli's, the latter reached his
conclusions independently.



VI. TWO PSEUDO-SCIENCES--ALCHEMY AND ASTROLOGY

In recent chapters we have seen science come forward with
tremendous strides. A new era is obviously at hand. But we shall
misconceive the spirit of the times if we fail to understand that
in the midst of all this progress there was still room for
mediaeval superstition and for the pursuit of fallacious ideals.
Two forms of pseudo-science were peculiarly prevalent --alchemy