t of the three auditory ossicles] was removed and a
pointed piece of hay about an inch in length was attached to the end of
the incus [the middle of the three auditory ossicles]. Upon moistening
the membrana tympani [membrane of the ear drum] and the ossiculae with a
mixture of glycerine and water the necessary mobility of the parts was
obtained, and upon singing into the external artificial ear the piece of
hay was thrown into vibration, and tracings were obtained upon a plane
surface of smoked glass passed rapidly underneath. While engaged in
these experiments I was struck with the remarkable disproportion in
weight between the membrane and the bones that were vibrated by it. It
occurred to me that if a membrane as thin as tissue paper could control
the vibration of bones that were, compared to it, of immense size and
weight, why should not a larger and thicker membrane be able to vibrate
a piece of iron in front of an electro-magnet, in which case the
complication of steel rods shown in my first form of telephone, Fig. 3,
could be done away with, and a simple piece of iron attached to a
membrane be placed at either end of the telegraphic circuit.

Figure 6 shows the form of apparatus that I was then employing for
producing undulatory currents of electricity for the purpose of multiple
telegraphy. A steel reed, A, was clamped firmly by one extremity to the
uncovered leg _h_ of an electro-magnet E, and the free end of the reed
projected above the covered leg. When the reed A was vibrated in any
mechanical way the battery current was thrown into waves, and electrical
undulations traversed the circuit B E W E', throwing into vibration the
corresponding reed A' at the other end of the circuit. I immediately
proceeded to put my new idea to the test of practical experiment, and
for this purpose I attached the reed A (Fig. 7) loosely by one extremity
to the uncovered pole _h_ of the magnet, and fastened the other
extremity to the centre of a stretched membrane of goldbeaters' skin
_n_. I presumed that upon speaking in the neighbourhood of the membrane
_n_ it would be thrown into vibration and cause the steel reed A to move
in a similar manner, occasioning undulations in the electrical current
that would correspond to the changes in the density of the air during
the production of the sound; and I further thought that the change of
the density of the current at the receiving end would cause the magnet
there to attract the reed