interruption of the current. From these and other discoveries which had
been made by Noad, Wertheim, Marrian, and others, Reis knew that if
the current which had been interrupted by his vibrating diaphragm were
conveyed to a distance by a metallic circuit, and there passed through
a coil like that of Page, the iron needle would emit a note like that
which had caused the oscillation of the transmitting diaphragm. Acting
on this knowledge, he constructed a rude telephone.

Dr. Messel informs us that his first transmitter consisted of the bung
of a beer barrel hollowed out in imitation of the external ear. The cup
or mouth-piece thus formed was closed by the skin of a German sausage to
serve as a drum or diaphragm. To the back of this he fixed, with a
drop of sealing-wax, a little strip of platinum, representing the
hammer-bone, which made and broke the metallic circuit of the current as
the membrane oscillated under the sounds which impinged against it. The
current thus interrupted was conveyed by wires to the receiver, which
consisted of a knitting-needle loosely surrounded by a coil of wire
fastened to the breast of a violin as a sounding-board. When a musical
note was struck near the bung, the drum vibrated in harmony with the
pitch of the note, the platinum lever interrupted the metallic circuit
of the current, which, after traversing the conducting wire, passed
through the coil of the receiver, and made the needle hum the original
tone. This primitive arrangement, we are told, astonished all who heard
it. [It is now in the museum of the Reichs Post-Amt, Berlin.]

Another of his early transmitters was a rough model of the human ear,
carved in oak, and provided with a drum which actuated a bent and
pivoted lever of platinum, making it open and close a springy contact
of platinum foil in the metallic circuit of the current. He devised some
ten or twelve different forms, each an improvement on its predecessors,
which transmitted music fairly well, and even a word or two of speech
with more or less perfection. But the apparatus failed as a practical
means of talking to a distance.

The discovery of the microphone by Professor Hughes has enabled us to
understand the reason of this failure. The transmitter of Reis was based
on the plan of interrupting the current, and the spring was intended to
close the contact after it had been opened by the shock of a vibration.
So long as the sound was a musical tone it proved efficien