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02.11
Electrical
Technology Comes to the Laboratory
By
Frederik nebeker,
IEEE History Center
Scientific laboratories were
radically transformed in the early decades of
the 20th century by the coming of
electrical and electronic technologies.
First of all, electrification of
the laboratory, which began in the last decade
of the 19th century, brought electric
lighting, which made a great difference by
extending working hours and making uniform
illumination possible at a optimal level.
Electric heating was valuable for space heating,
and even more valuable for localized heating as
in ovens, incubators, sterilizers, dryers, and
evaporators. Ventilation and air conditioning,
with humidity control, could be very important
in some types of work, and
refrigeration was often vital in biological
research. And
electric motors could be used in many ways,
as in pumps, fans, stirrers, agitators, and
pulverizers.
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A 1920 test
instrument (an impedance unbalance measuring
set).
Photo:
Courtesy IEEE History Center |
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The most obvious change to the
appearance of the laboratory in the first half
of the 20th century was the
proliferation of instruments. Many instruments
fit the following general description: a
transducer (in this context usually called a
sensor) converts the physical quantity of
interest into an electric current, and the
current, through the magnetic field it
generates, rotates a magnetic needle mounted in
front of a scale. In this or other ways almost
any physical quantity—velocity, acceleration,
light, sound, pressure, temperature, electric
field, magnetic field—can readily be measured.
Instruments to measure
non-electrical quantities could draw on these
techniques once a transducer had converted the
quantity of interest to an electrical or
magnetic quantity. There were thermometers,
pressure sensors, strain gauges, hydrometers,
spectrographs, calorimeters, dynamometers (for
measuring forces or torques), ergometers (for
measuring mechanical power), extensometers,
pyrometers, and katharometers (for determining
the composition of a gas mixture by measuring
thermal conductivity). Engineers continually
added to the quantities that could be measured
electrically. In 1934 Arnold Beckman developed a
pH meter, using electronic means to measure
accurately the acidity or alkalinity of a
solution, and in 1941 he developed a
spectrophotometer for use in determining the
chemical composition of a sample based on the
wavelengths of light reflected.
One of the great advances of the
20th century was
Lee de Forest's invention in 1906 of the
triode
electron tube. About the time of World War I
it began to be used as an amplifier in several
contexts, notably radio and long-distance
telephony. It was soon incorporated into many
measuring instruments, as it could, by
amplifying the signal coming from the sensor,
make them much more sensitive.
Another way in which
laboratories were changed in the first half of
the 20th century was the introduction
of new imaging devices. Prominent among these
was the oscilloscope. It got its start in 1897
when the German physicist Ferdinand Braun
constructed the first cathode-ray tube in order
to study the rapid variations of electrical
currents.
Until the late 1920s researchers had to
construct their own oscilloscopes, combining a
cathode-ray tube with special-purpose circuitry,
but commercial oscilloscopes came on the market
in the late 1920s, and they soon became a
standard part of laboratory instrumentation.
Other new forms of imaging were
x-ray machines (from turn of the century),
ultraviolet microscopes (from the late 1920s),
and electron microscopes (from the late 1930s).
Two oscilloscopes in
use.
Photo:
Courtesy IEEE History Center
There were many other new instruments.
Centrifuges and ultracentrifuges allowed
experimenters to separate the constituents of a
solution, and electrophoresis, introduced in the
late 1930s, was another invaluable analytic
technique. Together, the new instrumentation
changed not only the appearance of scientific
laboratories, but also the nature of the
investigations themselves, especially by
facilitating quantification and by providing new
means of imaging.
Frederik Nebeker is Senior
Research Historian at the IEEE History Center at
Rutgers University in New Brunswick, N.J. Visit
the IEEE History Center's Web page at:
www.ieee.org/organizations/history_center.
Comments may be submitted to
todaysengineer@ieee.org.
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