An introduction to mathematics, by A. N. Whitehead.

34 INTRODUCTION TO MATHEMATICS
same law holds for electric charges-laws
curiously analogous to that of gravitation.
In 1820, Oersted, a Dane, discovered that
electric currents exert a force on magnets,
and almost immediately afterwards the
mathematical law of the force was correctly
formulated by Ampère, a Frenchman, who
also proved that two electric currents exerted
forces on each other. "The experimental investigation by which Ampère established the
law of the mechanical action between electric
currents is one of the most brilliant achievements in science. The whole, theory and
experiment, seems as if it had leaped, fullgrown and full armed, from the brain of
the 'Newton of Electricity.' It is perfect
in form, and unassailable in accuracy, and it
is summed up in a formula from which all
the phenomena may be deduced, and which
must always remain the cardinal formula of
electro-dynamics." *
The momentous laws of induction between
currents and between currents and magnets
were discovered by Michael Faraday in 1831 -32. Faraday was asked: "What is the use
of this discovery?" He answered: "What is
the use of a child-it grows to be a man."
Faraday's child has grown to be a man and
is now the basis of all the modern applications
* Electricity and Magnetism, Clerk Maxwell, Vol. II., ch. iii.