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T
he invention of the electric
battery in 1799 opened
up whole new fields of
scientific research. In Denmark,
Hans Christian Ørsted accidentally
discovered a connection between
electricity and magnetism. At
London’s Royal Institution,
Michael Faraday imagined the
shapes of magnetic fields, and
invented the world’s first electric
motor. In Scotland, James Clerk
Maxwell picked up Faraday’s
ideas and figured out the complex
mathematics of electromagnetism.
Seeing the invisible
Invisible forms of electromagnetic
waves were discovered before
they were understood or the laws
governing their behavior were
figured out. Working in Bath,
Britain, German astronomer
William Herschel used a prism to
separate the various colors of
sunlight to study their
temperatures; he found that his
thermometer showed a higher
temperature beyond the red end of
the visible spectrum. Herschel had
stumbled upon infrared radiation,
and ultraviolet radiation was
discovered the following year—
proving that there was more to the
spectrum than visible light. In a
similar accidental way, Wilhelm
Röntgen later discovered X-rays in
his laboratory in Germany. British
physician Thomas Young devised
a clever double-slit experiment to
determine whether light is really a
wave or a particle. His discovery
of wavelike interference appeared
to settle the argument. In Prague,
Austrian physicist Christian
Doppler explained the colorof binary stars using the idea that
light is a wave with a spectrum
of various frequencies, laying out
the phenomenon now known as the
Doppler effect. Meanwhile, in Paris,
French physicists Hippolyte Fizeau
and Léon Foucault measured the
speed of light, and showed that it
travels more slowly through water
than through air.Chemical changes
British meteorologist John Dalton
tentatively suggested that atomic
weights might be a useful concept
for chemists and ventured to
estimate a few of them. Fifteen
years later, Swedish chemist Jöns
Jakob Berzelius drew up a much
more complete list of atomic
weights. His student, the German
chemist Friedrich Wöhler, turned
an inorganic salt into an organicINTRODUCTION
1800
1803
1821
1837
1811
1820
1842
Michael Faraday
discovers the principle
behind the
electric motor.John Dalton introduces the
idea of atomic weights.In the cliffs of Lyme
Regis, Mary Anning finds
the skeleton of the first
known ichthyosaur.German explorer
Alexander von
Humboldt introduces
the idea of ecology.Hans Christian Ørsted
discovers that when a
current is switched on,
a nearby compass
needle flickers.Astronomer William
Herschel discovers
infrared radiation.Christian Doppler
explains why binary
stars are colored.Louis Agassiz
describes
an ice age.1845