When Aloysio
Galvani first stimulated the nervous fiber by the accidental contact of two
heterogeneous metals, his contemporaries could never have anticipated that
the action of the voltaic pile would discover to us, in the alkalies, metals
of a silvery luster, so light as to swim on water, and eminently
inflammable; or that it would become a powerful instrument of chemical
analysis, and at the same time a thermoscope and a magnet. When Hygens
first observed, in 1678, the phenomenon of the polarization of light,
exhibited in the difference between the two rays into which a pencil of
light divides itself in passing through a doubly refracting crystal, it
could not have been foreseen that, a century and a half later, the great
philosopher Arago would, by his discovery of 'chromatic polarization', be
led to discern, by means of a small fragment of Iceland spar, whether solar
light emanates from a solid body or a gaseous covering, or
p 53
whether comets transmit light directly or merely by reflection.*
[Footnote] *Arago's Discoveries in the year 1811. -- Delambro's 'Histoire
de l'Ast.', p. 652. (Passage already quoted.)
An equal appreciation of all branches of the mathematical, physical, and
natural sciences is a special requirement of the present age, in which the
material wealth and the growing prosperity of nations are principally based
upon a more enlightened employment of the products and forces of nature.
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