Audio and Acoustic DNA—Do You Know Your Audio and Acoustic Ancestors? 7Dr. Michael I. Pupin of
Columbia University was
present at the Kennelly paper.
Pupin mentioned Oliver
Heaviside’s use of the word
impedance in 1887. This
meeting established the cor-
rect definition of the word
and established its use within
the electric industry. Ken-
nelly’s paper, along with the
ground-work laid by Oliver
Heaviside in 1887, was instrumental in introducing the
terms being established in the minds of Kennelly’s peers.
The truly extraordinary
Arthur Edwin Kennelly
(1861–1939) left school at the
age of thirteen and taught him-
self physics while working as a
telegrapher. He is said to “have
planned and used his time with
great efficiency,” which is evi-
denced by his becoming a mem-
ber of the faculty at Harvard in
1902 while also holding a joint
appointment at MIT from
1913–1924. He was the author of ten books and the
co-author of eighteen more, as well as writing more
than 350 technical papers.
Edison employed A.E. Kennelly to provide physics
and mathematics to Edison’s intuition and cut-and-try
experimentation. His classic AIEE paper on impedance
in 1893 is without parallel. The reflecting ionosphere
theory is jointly credited to Kennelly and Heaviside and
known as the Kennelly-Heaviside layer. One of Ken-
nelly’s Ph.D. students was Vannevar Bush, who ran
American’s WWII scientific endeavors.
In 1893 Kennelly proposed impedance for what had
been called apparent resistance, and Steinmetz sug-
gested reactance to replace inductance speed and watt-
less resistance. In the 1890 paper, Kennelly proposed
the name henry for the unit of inductance. A paper in
1892 that provided solutions for RLC circuits brought
out the need for agreement on the names of circuit ele-
ments. Steinmetz, in a paper on hysteresis, proposed the
term reluctance to replace magnetic resistance. Thus, by
the turn of the 20th century the elements were in place
for scientific circuit analysis and practical realization in
communication systems.
Arthur E. Kennelly’s writings on impedance were
meaningfully embellished by Charles Proteus Stein-
metz’s use of complex numbers. Michael Pupin, George
A. Campbell, and their fellow engineers developed filter
theory so thoroughly as to be worthwhile reading today.
Steinmetz was not at the April 18, 1893 meeting, but
sent in a letter of comment which included,It is, however, the first instance here, so far as I
know, that the attention is drawn by Mr. Kennelly
to the correspondence between the electric term
“impedance” and the complex numbers.
The importance hereof lies in the following:
The analysis of the complex plane is very well
worked out, hence by reducing the technical
problems to the analysis of complex quantities
they are brought within the scope of a known
and well understood science.The fallout from this seminal paper, its instantaneous
acceptance by the other authorities of the day, its
coalescing of the earlier work of others, and its utiliza-
tion by the communication industry within a decade,
makes it easily one of the greatest papers on audio ever
published, even though Kennelly’s purpose was to aid
the electric power industry in its transmission of energy.
The generation, transmission, and distribution of
electromagnetic energy today has
no meaning in itself, but only
gains meaning if information is
conveyed, thus the tragedy of the
use of mankind’s precious
resources to convey trash.
Nikola Tesla (1856–1943)
working with Westinghouse
designed the AC generator that
was chosen in 1893 to power the
Chicago World’s FairBell Laboratories and Western ElectricThe Univer-
sity of Chi-
cago, at the
end of the
turn of the
19th century
into the 20th
century, had
Robert Milli-
kan, Amer-
ica’s foremost physicist. Frank
Jewett, who had a doctorate in physics from MIT, and
now worked for Western Electric, was able to recruit
Millikan’s top students.