Hughes' experimental apparatus is of an amusingly simple description.
He has no laboratory at home, and all his experiments were made in the
drawing-room. His first microphones were formed of bits of carbon
and scraps of metal, mounted on slips of match-boxes by means of
sealing-wax; and the resonance pipes on which they were placed to
reinforce the effect of minute sounds, were nothing more than children's
toy money boxes, price one halfpenny, having one of the ends knocked
out. 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.
The weight of the crayon suffices to give the required pressure on the
contacts, both upper and lower, for the upper end of the Pencil should
lean against the inner wall of the cup in the upper bracket. The
brackets are fixed to an upright board of light, dry, resonant
pine-wood, let into a solid base of the same timber. The baseboard is
with advantage borne by four rounded india-rubber feet, which insulate
it from the table on which it may be placed. To connect the microphone
up for use, a small voltaic battery, say three cells (though a single
cell will give surprising results), and a Bell speaking telephone are
necessary. A wire is led from one of the ca