Émilie du Châtelet · Science
Du Châtelet’s 1737 essay for the Academy of Sciences prize on the nature of fire: written in secret, entered against Voltaire’s own entry, arguing that heat and light are distinct effects and anticipating what we would call infrared - and the courage of an anonymous submission by a woman shut out of the Academy.
In 1737 the Royal Academy of Sciences in Paris set its prize competition on a deep and unsettled question: the nature and propagation of fire. Fire, in the physics of the day, was mysterious - was it a substance, a kind of matter, or a state of motion? Did it have weight? What was the relation between the fire we feel as heat and the fire we see as light? Du Châtelet decided to compete. But there was an obstacle at home: Voltaire was also preparing an entry, and the two had been experimenting on fire together at Cirey. Coming to disagree with his approach, and wanting to test her own ideas without deference to his, she wrote her essay in secret, working at night after the household slept, and submitted it to the Academy without his knowledge. It was, in every sense, her own.
One of du Châtelet’s central conclusions was that light and heat are two different and independent effects, not simply two faces of one thing. We casually run them together - fire is hot and bright - but she pressed the distinction: there is light that is not notably hot, and heat where there is no light. Building on Newton’s demonstration that white light is a mixture of coloured rays, she reasoned about how heat is distributed among them and concluded that the heating power and the illuminating power of fire come apart. This mattered because it broke the lazy identification of ‘fire’ with a single simple quality. If heat and light are separable effects, then fire is not one thing with one essence but a name for a cluster of distinct phenomena that have to be studied separately. Her willingness to divide what common sense fused is the mark of a real investigator - and it set up her most prescient idea.
The prize went to Leonhard Euler and two others; neither du Châtelet nor Voltaire won. But the story has a remarkable ending. The Academy was impressed enough by du Châtelet’s essay that, at the urging of the naturalist Réaumur, it published her Dissertation sur la nature et la propagation du feu at its own expense alongside the winners - and Voltaire arranged for his to appear too. So a woman who could not be a member of the Academy, who had entered its competition anonymously and in secret, became one of the first women to have a scientific work published under the Academy’s auspices. The anonymity had been necessary: a submission judged on its merits, not prejudged by the sex of its author. When the authorship became known, the essay stood as public proof that a woman could do original physical science at the highest level of the age. The secrecy was not timidity; it was strategy, in a world built to keep her out.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that du Châtelet secretly entered the 1737 Academy prize on fire (against Voltaire’s own entry), argued that light and heat are distinct effects, and anticipated invisible heating rays - infrared. Explain her main conclusions and why entering anonymously mattered for a woman of her time.
Leads to Francis Bacon.
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