Émilie du

Châtelet

Jo Sibley

Gabrielle Émilie Le Tonnelier de

Breteuil, marquise du Châtelet

17 December 1706 – 10 September 1749

• Born Gabrielle Émilie Le Tonnelier de Breteuil, the daughter

of a lesser French nobleman in the court of Louis XIV.

• Married by arrangement, aged 18, to Marquis Florent-

Claude du Chastellet-Lomont, thus becoming the Marquise

du Chastellet.

• Bore him three children, died following the birth of her fourth

child.

“love of learning is the most necessary passion ... in it lies our happiness. It's a sure remedy for what ails us, an unending source of pleasure.”

Du Châtelet’s early education

Probably attended a Paris convent school, where she

learned Italian, Latin and English, as well as appropriate

etiquette for her état.

Her father provided tutors for her, significantly family friend

M. de Mezieres, who fostered her interest in mathematics.

Du Châtelet maintained her interest in mathematics,

philosophy and physics and sought an education in these

with renewed vigour following the birth of her first three

children.

Du Châtelet’s education

Du Châtelet studied under Pierre Louis de

Maupertuis, renowned mathematician and

astronomer of the time.

The subject of the infinitely

small led her to a dispute with

tutor Samuel Koenig. Later, this

exacerbated a dispute over her

book, Institutions de physique.

Alexis Clairaut became Du Châtelet’s

tutor from 1735. His work with

Maupertuis, argued against Newton’s

model of the shape of the Earth.

I would have

women

participate in all

human rights,

especially those

of the mind.

“If I were king, I would redress

an abuse which cuts back, as it

were, one half of human kind.

Du Châtelet’s passions

The marquise was determined not to

let society’s bias against her gender

get in the way of her studies.

As was the way of the time, having

provided heirs for her husband, she

took a series of lovers, most

importantly the scandalous

playwright, Voltaire.

Their passionate affair matured into a lifelong working

relationship, with Voltaire living for much of the time at the

Du Châtelet residence, Chateau de Cirey.

Du Châtelet’s passions

The marquise was formidable in

debate, and was an advocate for

education for women, especially

for French women to receive a

secondary education as she had;

unusual for the time.

She was an accomplished

gambler, devising a version of

‘derivatives’ to raise money to pay

for her gambling habits.

Du Châtelet and Voltaire built a

huge library together at Cirey

and performed experiments

together investigating the

nature of fire.

This frontispiece from Voltaire’s

work on Newton’s philosophy

shows the Marquise as his

muse, reflecting the light of

Newton’s inspiration onto his

writing desk.

Du Châtelet’s work

Du Châtelet’s work In 1737, Du Châtelet published a

paper; ‘Dissertation sur la nature

et la propagation du feu’, based on

her research with Voltaire at Cirey.

The paper predicted the existence

of infrared radiation.

We now know that the total momentum of a system is

conserved; none is lost to friction. Momentum cannot transfer

between different forms; there is no potential momentum.

Du Châtelet’s work – kinetic energy In the early 18th

century the idea

of energy, as a

transferable currency

between different

systems, was still in

its infancy, with

momentum instead

being the focus of

attention.

Mechanical energy, kinetic and potential, may be lost to

another form, but the total is conserved in time.

Mme. du Châtelet’s contribution was the hypothesis of the

conservation of total energy, as distinct from momentum.

The verification that Kinetic energy is mass(velocity)2

came from Du Châtelet’s reworking of Leibniz’s ideas, using

an experiment by Gravesande.

Du Châtelet’s work – kinetic energy

Gravesande experiment

Du Châtelet’s work – kinetic energy

Re-creating the

experiment in the

classroom:

• Constant acceleration

due to gravity

• If dropped from rest

from a height H, the

speed on impact is

𝐻

GCSE

Kinematics

opportunity!

Du Châtelet’s work – kinetic energy

Volume of spherical cap

=1

6𝜋ℎ 3𝑎2 + ℎ2

=1

24𝜋ℎ 3𝑑2 + 4ℎ2

Re-creating the experiment in

the classroom:

• Constant acceleration due

to gravity

• If dropped from rest from a

height H, the speed on

impact is 𝐻

• Consider depth of

impression or volume of

depression?

Prove using

solids of

revolution?

Mechanical energy, kinetic and potential, may be lost to

another form, but the total is conserved in time.

Mme. du Châtelet’s contribution was the hypothesis of the

conservation of total energy, as distinct from momentum.

The verification that Kinetic energy is mass(velocity)2

came from Du Châtelet’s reworking of Leibniz’s ideas, using

an experiment by Gravesande.

Du Châtelet’s work – kinetic energy

Gravesande experiment

Mme. du Châtelet’s contribution was the hypothesis of the

conservation of total energy, as distinct from momentum.

Without this additional consideration, problems such as the

collision and scattering of two particles cannot be fully

resolved.

Du Châtelet’s work – kinetic energy

Before After During

Du Châtelet’s translation of Newton’s

Principia into French was the definitive

text into this century.

Du Châtelet’s work

She did not simplify any of

his calculations and in fact

expanded on some of the

calculations, adding her

own proofs and diagrams

and a challenging

‘Algebraic Commentary’

which included her work on

kinetic energy.

In 1748, Du Châtelet was living at Lunéville

with Voltaire and his retinue.

She worked long hours at her studies,

taking them immensely seriously and rarely

breaking away during the day.

The completion of her work

She began an affair with a young poet,

Jean Francois Saint-Lambert, and soon fell

pregnant with his child.

Voltaire helped her to convince her husband that the child

was his. The child, a girl named Stanislas-Adélaide, was born

on 3rd September 1749.

Voltaire wrote:

The completion of her work

“The little girl arrives while her mother

was at her writing desk, scribbling some

Newtonian theories, and the newly born

baby was placed temporarily on a quarto

volume of geometry, while her mother

gathered together her papers and was put

to bed”

Gabrielle Émilie Le Tonnelier

de Breteuil, marquise du

Châtelet, died on 10th

September 1749, aged just

42.

Her husband, Saint-Lambert

and her long-time companion

Voltaire were all at her side.

Du Châtelet’s final days

About MEI

• Registered charity committed to improving

mathematics education

• Independent UK curriculum development body

• We offer continuing professional development

courses, provide specialist tuition for students

and work with industry to enhance mathematical

skills in the workplace

• We also pioneer the development of innovative

teaching and learning resources