FARADAY AND HIS INFLUENCE ON OUR EVERYDAY LIFE. 209
and sisters. Although so fully occupied with scientific work he
still kept in touch with life in general. His special enjoyment
was an occasional visit to the theatre with his wife. On making
one of his discoveries Faraday danced with joy, and proposed to
his laboratory attendant a visit to the theatre, giving him the
choice. "Oh ! let it be Astley's to see the horses," was the
reply. For relaxation on some evenings Faraday would take his
wife and his niece, Miss Reid, to the Zoological Gardens. The
monkeys amused him ; Miss Reid says "We have seen him laugh
till the tears ran down his cheeks as he watched them."
The Discovery of Electro-magnetic Induction.
The principle of Electro-magnetic Induction has led, during the
past century, to changes in the life of man more rapid and
numerous than in any other century. In 1791, the year of Fara-
day's birth, Galvani published his observations on the muscular
contractions of frogs' legs. This led to voltaic methods of pro-
ducing steady currents of electricity. Up to this time, in-
stantaneous currents only had been produced by discharge of the
Leyden jar. When Faraday began his electro-magnetic researches
in 1820. two fundamental facts were known—(1) Oersted's dis-
covery that a current in a wire deflected a magnetic needle ; (2)
Ampere's demonstraton that currents in neighbouring wires
exerted mechanical forces on each other. Faraday's diary (25
Dec, 1821) records the rotation of a wire carrying a current by
means of the earth's magnetic field. On November 22, 1824,,
Arago announced his discovery that a revolving copper plate
caused a magnetic needle suspended above it to rotate in the
same direction. Faraday (Dec. 28, 1824), not wishing to be beaten
in this field, tried to affect a current flowing in a coil by the
approach of a magnet. He detected no action. On November
28, 1825, he tried to make a current in a wire induce a current in
another wire—again without success. At intervals until 1831
he returned repeatedly to the attack—only to fail. Between these
attacks he investigated various problems in chemistry and in
other fields. Finally, on August 29, 1831, he recorded that he
made an iron ring. On it he wound two separate coils. One was
connected to a distant wire passing over a magnetic needle.
When he passed a current through the other coil, the distant
needle vibrated and finally settled down in its original position.