With such childish and worthless materials he has conquered Nature
in her strongholds, and shown how great discoveries can be made. The
microphone is a striking illustration of the truth that in science any
phenomenon whatever may be rendered useful. The trouble of one
generation of scientists may be turned to the honour and service of the
next. Electricians have long had sore reasons for regarding a 'bad
contact' as an unmitigated nuisance, the instrument of the evil one,
with no conceivable good in it, and no conceivable purpose except to
annoy and tempt them into wickedness and an expression of hearty but
ignominious emotion. Professor Hughes, however, has with a wizard's
power transformed this electrician's bane into a professional glory and
a public boon. Verily there is a soul of virtue in things evil.
The commonest and at the same time one of the most sensitive forms of
the instrument is called the 'pencil microphone,' from the pencil or
crayon of carbon which forms the principal part of it. This pencil may
be of mercurialised charcoal, but the ordinary gas-carbon, which
incrusts the interior of the retorts in gas-works, is usually employed.
The crayon is supported in an upright position by two little brackets of
carbon, hollowed out so as to receive the pointed ends in shallow cups.
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