Electricity and Communication
Themes for Electricity and Communication:
- the task of the individual inventor
- the rise of science-based industry
- the impact of technology on social
Early history of electricity:
Franklin was one of many experimenting with static electricity in
Volta invented the voltaic pile in 1800. The idea came from Luigi
Galvani, an anatomist, who was dissecting a frog when the frog's
began to twitch. He thought it resulted from electrical action in
the vicinity, such as lightening, stimulating some kind of natural
Volta realized that the metal elements touching the frog's nerves might
be the source of the action. Over a period of several years he
out how to use this effect and produced the first continuous flow of
from a wet battery.
- Volta's discovery led quickly to the use of
to decompose water and to electroplating of metals. In 1810 Davy
created an electric arc between two terminals as a source of
A number of people tried to build telegraphs--using electric current to
ring bells, for example, but at first these were not practical.
- in 1820 Oersted
discovered that an electric current creates a magnetic field, and Ampere
started researching the interactions between the two. Faraday
this to make a disk rotate in 1831--the first motor (and generator) but
not a useful one.
Pixii invented the first effective generator in 1832, but it was
The first application of a magneto generator (one with a permanent
to power an arc light was a lighthouse
illuminating the Straits of Dover in 1862.
and Wheatstone telegraph
- Practical telegraphs were invented by Baron
and Jacobi in Russia and by Cooke
and Wheatstone in England--a five-needle system was tried in 1837
railway use and later simplified--railway signaling is very important
not very demanding. The five
needle system used moving needles to point to letters on a
operator didn't have to read code but you had to have six wires between
the two stations.
- In the U.S. Samuel
F. B. Morse used a simple machine--longer or shorter bursts of
pushed a pencil to make a mark on a moving paper tape. The
was rugged and much cheaper to construct, but the operator had to learn
code. By 1837 Morse was transmitting sinals for 10 miles, and in
1843 Congress funded a line between Baltimore and Washington.
line was not widely used, but the line between Washington and New York
- By 1850 the telegraph linked all the states
Mississippi except Florida. Lines were laid along railroad right
of ways, making it easy to get the infrastructure in place.
- The demand for railroad signaling was
news could be profitable. Newspapers competed on having the
information--it was revolutionary that a St. Louis newspaper could
President Polk's 1848 message to Congress within 24 hours.
recording telegraph (#55)
There was great eagerness to lay a submarine
between Europe and the U.S.--underwater lines already joined England
France. (For more of the story see Early
Cable History )
- Retired industrialist Cyrus Field took this
as a pet
project, and made his first try in 1857, but the cables were not high
and broke 330 miles out.
- The second attempt with improved cable and
for the cable drums started in June 1858, but again the cable broke
- Another attempt later that year was
cable ceased to function after about a month due to deterioration by
- In 1865 another attempt set out to lay a
nautical miles built in a single length--5000 tons of cable. A
ship was built to lay the cable, called The
Great Eastern (picture
of its cable-handling gear) . Only 600
from Newfoundland the cable broke, and while it was grappled a couple
times it could not be lifted all the way to the surface.
- In 1866 a new cable was finally successfully
the previous year's one was successfully grappled and raised and
the 1865 cable
The telegraph became the basis for an industry:
- During the Civil
War over 6 million messages were transmitted by some 15000
and by the end of 1865 more than 200,000 miles of telegraph line were
service. Increased demand led to the invention of duplex and
- Thomas Edison's first major invention, in
stock ticker, a special printing telegraph to transmit stock prices
lights had been invented early in the century, but without an
power source they weren't very interesting. A few were run by
in the 1830s and 1840s, but no further improvements were patented
1860 and 1870.
T. Gramme (France) invented the dynamo (generator using
in 1867 and also showed it could be run backwards as a motor.
was a model maker for a manufacturer of electrical devices; he didn't
a deep knowledge of the theory involved. He developed his dynamo
into a system particularly for powering an improved arc light invented
in Paris that required alternating current and high voltage. The
system was quite widely used in Europe, though it consumed carbons at a
very high rate.
- In 1878 Charles
F. Brush invented an arc lighting system with a better generator
a simple arc light. This was immediately useful for street lights
and other large spaces. Both Brush's company and one started a
later by two Philadelphia high school teachers--Elihu
Thomson and Edwin Houston--were commercially successful.
- In 1873 research on generators led to the
effective electric motors. Simple motors had been built as
toys 40 years earlier, but power from a battery was over 20 times more
expensive than power from a steam engine.
light was fairly sucessful in cities for small-scale lighting,
arc lighting was too bright. A number of inventors starting
for an alternative, including Thomas Edison.
This page written and copyright Pamela
last updated 10/21/2005