Claude Louis Marie Henri Navier
Born: 10 Feb 1785 in Dijon, France Died: 21 Aug 1836 in Paris,
France
ClaudeLouis Navier's father was a lawyer who was a
member of the National Assembly in Paris during the time of the French
Revolution. However Navier's father died in 1793 when Navier was only eight
years old. At this time the family were living in Paris but after Navier's
father died, his mother returned to her home town of ChalonsurSaône and left
Navier in Paris to be cared for by her uncle Emiland Gauthey.
Emiland Gauthey was a civil engineer who worked at the Corps
des Ponts et Chaussées in Paris. He was considered the leading civil engineer in
France and he certainly gave Navier an interest in engineering. Despite
encouraging Navier to enter the École Polytechnique, Gauthey seems not to have
been that successful in teaching Navier, who may just have been a late
developer, for he only just scraped into to École Polytechnique in 1802.
However, from almost bottom place on entry, Navier made such progress in his
first year at the École Polytechnique that he was one of the top ten students at
the end of the year and chosen for special field work in Boulogne in his second
year.
During this first year at the École Polytechnique, Navier was
taught analysis by Fourier who had a remarkable influence on the young man.
Fourier became a lifelong friend of Navier as well as his teacher, and he took
an active interest in Navier's career from that time on. In 1804 Navier entered
the École des Ponts et Chaussées and graduated as one of the top students in the
school two years later. It was not long after Navier's graduation that his
granduncle Emiland Gauthey died and Navier, who had left Paris to undertake
field work, returned to Paris, at the request of the Corps des Ponts et
Chaussées, to take on the task of editing Gauthey's works. Anderson writes in
[3]:
Over the next 13 years, Navier became recognised as a
scholar of engineering science. He edited the works of his granduncle, which
represented the traditional empirical approach to numerous applications in civil
engineering. In that process, on the basis of his own research in theoretical
mechanics, Navier added a somewhat analytical flavour to the works of Gauthey.
That, in combination with textbooks that Navier wrote for practicing engineers,
introduced the basic principles of engineering science to a field that
previously had been almost completely empirical.
Navier took charge of the applied mechanics courses at the
École des Ponts et Chaussées in 1819, being named as professor there in 1830. He
did not just carry on the traditional teaching in the school, but rather he
changed the syllabus to put much more emphasis on physics and on mathematical
analysis. In addition, he replaced Cauchy as professor at the École
Polytechnique from 1831. His ideas for teaching were not shared by all, however,
and soon after his appointment to the professorship at the École Polytechnique
Navier became involved in a dispute with Poisson over the teaching of Fourier's
theory of heat.
A specialist in road and bridge building, he was the first to
develop a theory of suspension bridges which before then had been built to
empirical principles. His major project to build a suspension bridge over the
Seine was, however, to end in failure. The real reason that the project ran into
difficulties was that the Municipal Council never supported it. Despite this it
went ahead but, when the bridge was almost complete, a sewer ruptured at one end
causing a movement of one of the bridge supports. The problem was not considered
a major one by the Corps des Ponts et Chaussées who reported that repairs were
straightforward, but the Municipal Council were looking for an excuse to stop
the project and they had the bridge dismantled.
Navier is remembered today, not as the famous builder of
bridges for which he was known in his own day, but rather for the NavierStokes
equations of fluid dynamics. He worked on applied mathematics topics such as
engineering, elasticity and fluid mechanics and, in addition, he made
contributions to Fourier series and their application to physical problems. He
gave the well known NavierStokes equations for an incompressible fluid in 1821
while in 1822 he gave equations for viscous fluids.
We should note, however, that Navier derived the NavierStokes
equations despite not fully understanding the physics of the situation which he
was modelling. He did not understand about shear stress in a fluid, but rather
he based his work on modifying Euler's equations to take into account forces
between the molecules in the fluid. Although his reasoning is unacceptable
today, as Anderson writes in [3]:
The irony is that although Navier had no conception of shear
stress and did not set out to obtain equations that would describe motion
involving friction, he nevertheless arrived at the proper form for such
equations.
Navier received many honours, perhaps the most important of
which was election to the Académie des Sciences in Paris in 1824. He became
Chevalier of the Legion of Honour in 1831.
Finally we should say a little of Navier's political position.
Of course he lived through a period when there was great political movements
throughout Europe and in France in particular. The two men who had the most
influence on Navier's political thinking were Auguste Comte, the French
philosopher known as the founder of sociology and of positivism, and Henri de
SaintSimon who started the SaintSimonian movement which proposed a socialist
ideology based on society taking advantage of science and technology.
Comte had been educated at the École Polytechnique, entering in
1814, where he had studied mathematics. Navier appointed him as one of his
assistants at the École Polytechnique and this connection was to see Navier
become an ardent supporter of the ideas of Comte and SaintSimon. Navier
believed in an industrialised world in which science and technology would solve
most of the problems. He also took a stand against war and against the
bloodletting of the French Revolution and the military aggression of Napoleon.
From 1830 Navier was employed as a consultant by the government
to advise on how science and technology could be used to better the country. He
advised on policies of road transport, the construction of both roads and
railways. His many reports show both his remarkable abilities as an engineer
coupled with his strong political views on building an industrialised society
for the advantage of all.
Article by: J J O'Connor and E F Robertson
May 2000
