the receiving instrument. Such a device when slightly
jarred, by the voice or other means, causes abrupt variation in the
resistance of the line, and will transmit speech.

Early Conceptions. The conception of the possibility and
desirability of transmitting speech by electricity may have occurred
to many, long prior to its accomplishment. It is certain that one
person, at least, had a clear idea of the general problem. In 1854,
Charles Bourseul, a Frenchman, wrote: "I have asked myself, for
example, if the spoken word itself could not be transmitted by
electricity; in a word, if what was spoken in Vienna might not be
heard in Paris? The thing is practicable in this way:

[Illustration: Fig. 4. Reis Transmitter]

"Suppose that a man speaks near a movable disk sufficiently flexible
to lose none of the vibrations of the voice; that this disk
_alternately makes and breaks_ the connection from a battery; you may
have at a distance another disk which will simultaneously execute the
same vibrations." The idea so expressed is weak in only one
particular. This particular is shown by the words italicized by
ourselves. It is impossible to transmit a complex series of waves by
any simple series of makes and breaks. Philipp Reis, a German, devised
the arrangement shown in Fig. 4 for the transmission of sound, letting
the make and break of the contact between the diaphragm _1_ and the
point _2_ interrupt the line circuit. His receiver took several forms,
all electromagnetic. His success was limited to the transmission of
musical sounds, and it is not believed that articulate speech ever was
transmitted by such an arrangement.

It must be remembered that the art of telegraphy, particularly in
America, was well established long before the invention of the
telephone, and that an arrangement of keys, relays, and a battery, as
shown in Fig. 5, was well known to a great many persons. Attaching the
armatures of the relays of such a line to diaphragms, as in Fig. 6, at
any time after 1838, would have produced the telephone. "The hardihood
of invention" to conceive such a change was the quality required.

[Illustration: Fig. 5. Typical Telegraph Line]

Limitations of Magneto Transmitter. For reasons not finally
established, the ability of the magneto telephone to produce large
currents from large sounds is not equal to its ability to produce
large sounds from large currents. As a receiving device, it is
unexcelled, and but slight impr