sing or opening the breach between
them, which is, as it were, the floodgate of the current.

The applications of the microphone were soon of great importance. Dr. B.
W. Richardson succeeded in fitting it for auscultation of the heart
and lungs; while Sir Henry Thompson has effectively used it in those
surgical operations, such as probing wounds for bullets or fragments of
bone, in which the surgeon has hitherto relied entirely on his delicacy
of touch for detecting the jar of the probe on the foreign body.
There can be no doubt that in the science of physiology, in the art of
surgery, and in many other walks of life, the microphone has proved a
valuable aid.

Professor Hughes communicated his results to the Royal Society in the
early part of 1878, and generously gave the microphone to the world. For
his own sake it would perhaps have been better had he patented and
thus protected it, for Mr. Edison, recognising it as a rival to
his carbon-transmitter, then a valuable property, claimed it as an
infringement of his patents and charged him with plagiarism. A spirited
controversy arose, and several bitter lawsuits were the consequence, in
none of which, however, Professor Hughes took part, as they were only
commercial trials. It was clearly shown that Clerac, and not Edison, had
been the first to utilise the variable resistance of powdered carbon or
plumbage under pressure, a property on which the Edison transmitter was
founded, and that Hughes had discovered a much wider principle, which
embraced not only the so-called 'semi-conducting' bodies, such as
carbon; but even the best conductors, such as gold, silver, and
other metals. This principle was not a mere variation of electrical
conductivity in a mass of material brought about by compression, but a
mysterious variation in some unknown way of the strength of an electric
current in traversing a loose joint or contact between two conductors.
This discovery of Hughes really shed a light on the behaviour of
Edison's own transmitter, whose action he had until then misunderstood.
It was now seen that the particles of carbon dust in contact which
formed the button were a congeries of minute micro-phones. Again it was
proved that the diaphragm or tympanum to receive the impression of
the sound and convey it to the carbon button, on which Edison had laid
considerable stress, was non-essential; for the microphone, pure and
simple, was operated by the direct impact of the sonorou