"Donald E. Kimberlin" <0004133373@mcimail.com> (06/02/91)
We can all hum that song made so popular by several singers up
to the inimitable Frank Sinatra. Through it, we can see Chicagoans
have always known how to "party hearty."
That's often our first thought about Chicago and what goes on
thre. Great convention town, as many of us know from direct
experience. Somehow, despite evidence that most of the early
developers of telecommunications devices in America started in
Chicago's environs, we never get a focus on the status of Chicago's
contributions to our technology.
It must have been a significant focus, for Chicago is also the
birthplace of every basic unit of electrical measurement the world
uses. Here's a quotation from Percy Dunsheath's "A History of
Electrical Engineering," (Faber & Faber, London, 1962, pp. 302-303):
"At the International Electrical Exposition held in Paris in
1881 much dissatisfaction with the postion was expressed by practical
electrical engineers, who were still using widely `Weber' to denote
the unit of current, measuring electrical pressure in terms of the
equivalent number of Daniell cells and resistance in terms of miles of
telegraph wire" <another book on the life of Wehrner von Siemens
somewhat immodestly suggests that he declined the honor of having
Georg Ohm's unit named the "Siemens."> "and the new names ampere, volt
and ohm were adopted." <But notice they are NOT capitalized at this
point. That has significance in the world of scholarly science, as
we'll see later.>
"In 1891 the <British> Board of Trade set up a Standards
Committee `for the measurement of electricity for use in trade' which
adopted the C.G.S. system of electrical units with the values of units
determined by the original British Association Committee and adopted
the names which that Committee had proposed: ohm, ampere, volt for the
units of electrical resistance, electric current and electric
pressure." <Notice the names are still not capitalized.>
"Two years later an important International Electrical
Congress was held in Chicago under the presidency of Helmholtz with
Britain represented by Preece, Ayrton, Silvanus Thompson and Alexander
Siemens.
"This Congress recommended the following as legal units:
"RESISTANCE. The Internationa Ohm based upon the ohm equal to
10e9 units of resistance of the C.G.S. system of electromagnetic
units represented by the resistance to an unvarying current by a
column of mercury at the temperature of melting ice 14.4521
grams in mass of a constant cross section and a length of
106.3 cm.
"CURRENT. The International Ampere, one-tenth of the unit of
current of the C.G.S. unit represented by the current which when
passed through a solution of nitrate of silver deposits silver at
the rate of 0.001118 of a gram per second.
"ELECTROMOTIVE FORCE. The International Volt, which is the
electromotive force that steadily applied will produce a current
of one International Ampere represented by 1000/1434 of the
electromotive force of a Clark's cell at 15 degrees Centigrade.
"The unit of quantity, the International Coulomb, was that quantity
transferred by one International Ampere fowing for one second.
"The unit of capacity, the International Farad, was the capacity
of a condenser which a charge of one International Coulomb would
raise by one International Volt.
"The unit of work, the International Joule, was 10e7 units of work
in the C.G.S. system or the energy expended when one International
Ampere flows through a resistance of one International Ohm for one
second.
"The unit of power, the International Watt, 10e7 units in the
C.G.S. system or the power when the expenditure of energy is at the
rate of one International Joule per second.
"The unit of induction, the International Henry, or the induction
in a circuit when a pressure of one International Volt is induced
by a change of one International Ampere per second."
Shortly later, Dunsheath writes, "By this time" (1908) the
same units of resistance, current and e.m.f. had been adopted by all
the principal countries if the world." <end of quotes>
(For those interested, these International units are ten times
larger than what we use everyday, which are called the "practical
units," based on the M.K.S. system of measurement instead of the
C.G.S. system used in the basic physics laboratory. We signify the
practical units by NOT capitalizing their names, while the larger
International Units are capitalized.
But be careful: Some units, like the Baud, are used as internationally
standardized and are capitalized anyway. However, not only do
telecomm people almost always write the term Baud incorrectly, they
typically horrobly misuse it, anyway. Your 2400 bps modem does NOT
transmit or receive 2400 "Baud," unless you want to play word games
about it doing so because it's operating full duplex! Regardless,
your 9600 NEVER transmits 9600 "Baud" in any event.)
While the units named in Chicago have undergone slight
adjustment in the intervening century, they remain the units we all
use daily in any aspect of telecommunications work. And I'll bet
those famous heads of science who met in Chicago in 1893 enjoyed the
fabled hospitality and great steaks of That Toddlin' Town, as well!