|
Charles, Jacques Alexandre César (1746-1823) was a French physicist and mathematician who is remembered for
his work on the expansion of gases and his pioneering contribution
to early ballooning.
Charles was born in Beaugency, Loiret, on 12 November 1746. He
became interested in science while working as a clerk in the
Ministry of Finance in Paris. Stimulated by Benjamin Franklin's
experiments with lightning and electricity, he constructed a range
of apparatus which he demonstrated at popular public lectures. He
also experimented with gases. He was elected to the French Academy
of Sciences in 1795 and later became Professor of Physics at the
Paris Conservatoire des Arts et Métiers. He died in Paris on 7
April 1823.
The Montgolfier brothers made their first experiments with
uncrewed hot-air balloons at Viadalon-les-Annonay in June 1783. On
hearing about them, Charles tried filling a balloon with hydrogen,
and with the brothers Nicolas and Anne-Jean Robert made the first
successful (uncrewed) experiment in August 1783. In November of that
year the Montgolfiers demonstrated their hot-air balloons in Paris,
and on 1 December Charles and Nicolas Robert made the first human
ascent in a hydrogen balloon. In later flights Charles ascended to
an altitude of 3,000 m/9,846 ft. On a tide of public acclaim he was
invited by King Louis XVI to move his laboratory to the Louvre -
patronage that Charles was to regret ten years later during the
French Revolution.
In about 1787 Charles experimented with hydrogen, oxygen and
nitrogen and demonstrated the constant expansion of these gases,
that is at constant pressure the volume of a gas is inversely
proportional to its temperature. He found that a gas expands by
1/273 of its volume at 0°C for each Centigrade (Celsius)
degree rise in temperature (implying that
at-273°C/-459.4°F, now known as absolute zero, a
gas has no volume). He did not publish his results, but communicated
them to the French physical chemist Joseph Gay-Lussac, who repeated
the experiments and made more accurate measurements. Unknown to the
two French scientists, John Dalton in
England was also about to embark on similar research. Dalton
deduced the same gas law in 1802, but the first to publish (six
months later) was Gay-Lussac. For this reason, the law became known
in France as Gay-Lussac's law but elsewhere it was, and still is,
generally known as Charles' law. Incidentally, Gay-Lussac continued
to emulate Charles by becoming a pioneer balloonist.
Charles devised or improved many scientific instruments. He
invented a hydrometer and a reflecting goniometer, and improved the
aerostat of Gabriel Fahrenheit (1686-1736) and the heliostat of W.J.
vans' Gravesande (1688-1742).
Author not available, Charles, Jacques Alexandre C?r
(1746-1823). , The Hutchinson Dictionary of Scientific
Biography, 01-01-1998.
|