have covered its
author with titles and scientific honours, and placed him above the
necessity of regular employment. He left America, and travelled from
place to place. For many years past, however, he has resided privately
in London, an eminent example of that modesty and simplicity which is
generally said to accompany true genius.

Mechanical invention is influenced to a very high degree by external
circumstances. It may sound sensational, but it is nevertheless true,
that we owe the microphone to an attack of bronchitis. During the thick
foggy weather of November 1877, Professor Hughes was confined to his
home by a severe cold, and in order to divert his thoughts he began to
amuse himself with a speaking telephone. Then it occurred to him that
there might be some means found of making the wire of the telephone
circuit speak of itself without the need of telephones at all, or
at least without the need of one telephone, namely, that used in
transmitting the sounds. The distinguished physicist Sir William
Thomson, had lately discovered the peculiar fact that when a current of
electricity is passed through a wire, the current augments when the wire
is extended, and diminishes when the wire is compressed, because in the
former case the resistance of the material of the wire to the passage of
the current is lessened, and in the latter case it becomes greater.

Now it occurred to Professor Hughes that, if this were so, it might
be possible to cause the air-vibrations of sound to so act upon a wire
conveying a current as to stretch and contract it in sympathy with
themselves, so that the sound-waves would create corresponding electric
waves in the current, and these electric waves, passed through a
telephone connected to the wire, would cause the telephone to give forth
the original sounds. He first set about trying the effect of vibrating a
wire in which a current flowed, to see if the stretching and compressing
thereby produced would affect the current so as to cause sounds in a
telephone connected up in circuit with the wire--but without effect.
He could hear no sound whatever in the telephone. Then he stretched
the wire till it broke altogether, and as the metal began to rupture he
heard a distinct grating in the telephone, followed by a sharp 'click,'
when the wire sundered, which indicated a 'rush' of electricity through
the telephone. This pointed out to him that the wire might be sensitive
to sound when in a state