Hearing the Field 213
it vanished in the steady state and only appeared the instant contact was made or broken,
and thus could easily be dismissed as a meaningless glitch.
Yet Faraday recognized it on the very first day he began his experiments; his mind was
evidently thoroughly prepared to recognize the effect, however transient. Though his diary
makes no explicit connection with his preceding experiments on sound, several clues
indicate their significance for his parallel experience in electromagnetism. His published
account compares the effect to an “ electrical wave ” ; he had just spent six months studying
in great detail the behavior of sound waves in various media. His careful consideration of
the state of those media and their effects on the resulting patterns seems to inform the
“ new electrical state or condition of matter ” he designates as “ the electro-tonic state ” that
is “ altogether the effect of the induction effect, and ceases as soon as the inductive
force is removed. ... This peculiar state appears to be a state of tension, and may be con-
sidered as equivalent to a current of electricity, at least equal to that produced either when
the condition is induced or destroyed. ”^39 Faraday ’ s electro-tonic state clearly is the “ state ”
he had sought in answer to Amp è re; he would go on to use it as an important element in
his further work on electromagnetism. Even his drawings of his vibrational and electro-
dynamic setups show similar geometries ( figure 13.12 ).
Six months after his discovery, on March 12, 1832, Faraday deposited in the safe of the
Royal Society a statement that would “ take possession as it were of a certain date, and a
long right, if they are confirmed by experiments, to claim credit for the views of that date, ”
even though he had already published the full experimental details (including his com-
ments on the electro-tonic state) in November, 1831. The crux of this sealed statement is
first that “ magnetic action is progress, and requires time, ” as does “ electric induction (of
tension) [electrostatic induction]. ” Faraday continues:I am inclined to compare the diffusion of magnetic forces from a magnetic pole, to the vibrations
upon the surface of disturbed water, or those of air in the phenomena of sound; i.e. I am inclined to
think the vibratory theory will apply to these phenomena, as it does to sound and most probably
to light.^40Here the strong relation between sound, electromagnetism, and now also light becomes
patent: Faraday summarizes his vision of physics, which he correctly anticipated would
take decades of his life to complete; his entries on electromagnetic induction became the
first paragraphs of his Experimental Researches in Electricity that eventually stretched to
3,362 paragraphs by 1855.
For his part, Wheatstone ’ s work on the velocities of transmission of sound and electric-
ity, combined with electromagnetic induction, led directly to his discovery of telegraphy
(1837) with William Cooke.^41 Wheatstone reentered Faraday ’ s story memorably on April
10, 1846. Scheduled to give a solo lecture on his electromagnetic chronoscope, at the very
last moment Wheatstone panicked and fled, as legend has it; it is said he spotted a notori-
ous heckler in the audience, though his own shyness may have been overwhelmed by the