FOURIER, J.(1768-1830) and POINSSON, S.D.(1781-1840)
Fourier was vborn in Auxerre in 1768 and died in Paris in 1830. The son of a
tailor, he was orphaned at the age of eight and educated in a military school
conducted by the Bendictines, where he was given a lectureship in mathematics.
He assisted in the promotion of the Frnch Revolution and was rewarded
by a chair at the Ecole Polytechnique. He resigned from this position so that
he, along with Monge, could accompany Napoleon on the Egyptuab expedition.
1798, he was appointedgovernor of Lower Ehypt. Fourier returned to france
victories and the capitulation of the French in 1801, Fourier returned to France
and was made prefect of Grenoble. It was while at Grenoble the he started his
experiments on heat.
In 1807, Fourier presented a paper before the French Academy of Sciences
that initiated a new and highly fruitful chapter in the history of mathematics.
The paper dealt with the practical problem of the flow of heat in metallic rods,
plates, and solid bodies. In the course of the presentation of the paper, Fourier
made the startling claim that any function, defined in a finite closed interval by
an arbitrarily drawn graph, can be resolved into a sum of sine and cosine
functions. To be more explicit, he claimed that any function whatever, no
n\matter how capriciously it is defined in the interval (-¥ð,¥ð), can be represented
in that interval by
where the a's and the b's are suitable real numbers. Such a series is known as a
trigonometric series, and was not new to the mathematicians of the time. Indeed,
a number of more ofr less well behaved functions had been shown to be
representable by such a series. But Fourier claimed that any function defined in
(-¥ð,¥ð) can be so represented. The savants at the Academy were very skeptical
of Fourier's claim, and the paper, which was judged by Lagrange, Laplace, and
Legendre, was rejedted. However, to encourage Fourier to develop his ideas
more carefully, the French Academy made the problem of heat propagation the
subject of a grand prize to be awarded in 1812. Fourier submitted a revised
paper in 1811, which was judged by a group containing, among others, the
former three judges, and the paper won the prize, though it was criticized for
lack of rigor and so was not recommended for publication in the Acakemy's
Poisson was born in Pithiviers in 1781 and died in Paris in 1840. He was educated by his father, a private soldier who on retirement received a small administrative post in his village and, when the French Revolution broke out, assumed the governing of the place. Relatives wished to press the young Poisson, much against his own wishes, onto medicine. The education was undertaken by an uncle, who started the boy off with pricking veins in cabbage leaves with
When he had perfected himself in this, he was graduated to
puting on blisters. But in almost the first case in which he did this by himself,
his patient died sithin a few hours. Although the docters assured hom that
"The event was a very common one," he vowed to have nothing more to do
with the profession.