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the Academy of Fine Arts and trained in the atelier
of Ingres. When Ingres took up his post at the French
Academy in Rome, Frénet followed. After his return to
France in 1837 he worked for some time in Paris; then
settled outside of Lyon where he undertook regional
commissions. Frénet, a committed Republican, became
politically active after the revolution of 1848. He was
the mayor of his small community and ran afoul of the
authorities for falsifying election returns in the plebiscite
of 1851. This effectively ended any hope for offi cial
painting commissions. He appears to have taken up
photography in the early 1850s, perhaps as a response
to the limitations to his career as a painter. Working with
the paper negative, salted paper print process, Frénet
made domestic portraits and intimate studies of infor-
mally posed family groups, as well as a small number
of landscapes. Examples of his photographic production
date to the 1850s and are limited to the paper process.
Kathleen Howe
FRESNEL, AUGUSTIN JEAN (1788–1827)
French scientist and inventor
Fresnel was born on 10 May 1788 in Broglie, France.
His father, Jacques Fresnel, was an architect who went
on to work on harbour construction at Cherbourg. In
1794 the political situation in France led to work on
the harbour being halted so the Fresnel family went to
Mathieu, a village north of Caen, where young Augustin
Fresnel spent the rest of his childhood. His parents were
Jansenists, and Augustin was brought up with strict
values in a stern atmosphere which would strongly
infl uence him throughout his life.
After elementary education by his parents, and sec-
ondary education in Caen he entered the École Poly-
technique in Paris in 1804 with a career in engineering
in mind. Two years later he progressed to the École
des Ponts et Chaussées, qualifying as a civil engineer.
He was employed fi rst in the Vendée and then on the
building of a major road through France connecting
Spain with northern Italy. However, he had a hobby: he
was fascinated by light and undertook experiments in
- In 1815, when Napoleon landed at Cannes with
some of his guards, Fresnel was so upset that he left his
engineering job and offered to fi ght for the King against
Napoleon. By 20 March Napoleon had reached Paris
putting Fresnel in a diffi cult position. As a consequence
he lost his engineering post and was put under police
surveillance. He had few options left but to return to his
home in Mathieu. In fact circumstances had conspired
to give Fresnel the free time he needed to concentrate
on his experiments with light. His work on optics soon
convinced him of the validity of the wave theory of light
which was, at that time, totally disregarded in favour of
the corpuscular theory. After Napoleon was defeated at
Waterloo, Fresnel was reinstated into his old engineer-
ing appointment. He was then only able to undertake
research on light in his vacations. He was transferred to
an engineering post in Rennes but continually requested
leave so that he could go to Paris to continue his scien-
tifi c investigations.
By applying mathematical analysis to his work Fres-
nel removed many of the objections to the wave theory
of light. He knew little about the contributions by other
scientists. He experimented with diffraction, making a
breakthrough when he attached a piece of black paper
to one edge of a diffracter and observed that then the
bright bands within the shadow vanished. From this he
correctly deduced that these bright bands were produced
by light coming from both edges of the diffracter but
since bright bands outside the shadow remained he
deduced that they must result from light refl ected from
only one edge of the diffracter. He published his fi rst
paper in October 1815 on his wave theory of light,
making a fi rst attempt to explain the phenomenon of
diffraction. He then applied the same mathematics
which worked for his diffraction experiments to give
theoretical results on interference patterns obtained by
refl ecting a light source with two mirrors. He verifi ed
the theoretical results by experiment. Much of this early
work was already essentially known, but Fresnel next
developed a new theory, publishing tentative results in
July 1816. After working for a while on polarisation of
light during 1817, he returned to his theories of diffrac-
tion when the Académie des Sciences announced that
the Grand Prix for 1819 would be awarded for work
on that topic. He was confi dent of his theory since his
mathematical deductions from the one simple hypoth-
esis led to results which he had verifi ed experimentally.
In his submission he calculated the intensity of light at
every point behind the diffracter using what were later
called Fresnel’s integrals.
In 1819 the committee to judge the Grand Prix
met consider Fresnel’s submission but most members
including the chairman Arago and Poisson believed in
the corpuscular model. However Poisson was fascinated
by Fresnel’s mathematics and discovered further con-
sequences beyond those which Fresnel had deduced.
Poisson showed that a bright spot would be seen in the
centre of the shadow. Arago asked that Poisson’s remark-
able predictions based on Fresnel’s model be tested.
Indeed the bright spot was seen exactly as Fresnel’s
theory predicted and the Grand Prix was awarded.
Fresnel zone plates, used in photography, rely on this
work. Despite this triumph for wave theory, polarisation
of light produced by refl ection still provided a strong
argument in favour of the corpuscular theory. Fresnel
and Arago, now very confi dent that they could explain
this effect with Fresnel’s theory, undertook further