The discovery of the electric current is due
to two Italians, Galvani in 1780, and Volta
in 1792. This great invention opened a new series of phenomena for investigation. The scientific world had now three separate, though allied, groups of occurrences on hand–-the effects of "statical" electricity arising from frictional electrical machines, the magnetic phenomena, and the effects due to electric currents. From the end of the eighteenth century onwards, these three lines of investigation were quickly interconnected and the modern science of electromagnetism was constructed, which now threatens to transform human life.
Mathematical ideas now appear. During the decade 1780 to 1789, Coulomb, a Frenchman,
proved that magnetic poles attract or repel each other, in proportion to the inverse square of their distances, and also that the
same law holds for electric charges–-laws curiously analogous to that of gravitation. In 1820, Öersted, 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, full-grown 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."Electricity and Magnetism, Clerk Maxwell, Vol. II.,
ch. iii.
The momentous laws of induction between currents and between currents and magnets were discovered by Michael Faraday in 1831–82.
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
of electricity. Faraday also reorganized the whole theoretical conception of the science. His ideas, which had not been fully understood by the scientific world, were extended and put into a directly mathematical form by Clerk Maxwell in 1873. As a result of his
mathematical investigations, Maxwell recognized that, under certain conditions, electrical vibrations ought to be propagated. He at once suggested that the vibrations which form light are electrical. This suggestion has
since been verified, so that now the whole theory of light is nothing but a branch of the
great science of electricity. Also Herz, a