Antoine Joseph Bernard Brunhes (pronounced: brune) (3 July 1867 – 10 May 1910) was a French geophysicist known for his pioneering work in paleomagnetism, in particular, his 1906 discovery of geomagnetic reversal. The Brunhes–Matuyama reversal is named for him.
Brunhes was educated at the École Normale Supérieure in Paris, from which he graduated as an agrégé qualified in physics. His thesis work was on internal crystalline reflection. He was appointed lecturer at the Université Lille Nord de France. Later he taught physics and electrical engineering at École Centrale de Lille from 1893 to 1895. He served as a professor at the University of Dijon, and at the Faculty of Science of Clermont Ferrand.
In November 1900, he was appointed as head of the Puy-de-Dôme Observatory, built on an extinct volcano in the Auvergne region of France, where he worked until his death in 1910. It was during his time at the observatory that he made the crucial observation that led to his discovery of geomagnetic reversal.
Discovery of geomagnetic field reversal
In 1905, he found that rocks in an ancient lava flow at Pontfarin in the commune of Cézens (part of the Cantal département) were magnetised in a direction almost opposite to that of the present-day magnetic field. From this, he deduced that the magnetic North Pole of the time was close to the current geographical South Pole, which could only have happened if the magnetic field of the Earth had been reversed at some point in the past.
In "Degradation of Energy," Brunhes presented his research on energy flow and soil erosion. He saw deforestation as a consequence of the privatization of communal land, lamenting the "tragedy of enclosure," which he saw as the result of private land owners not taking care to prevent soil loss.
With his brother Jean Brunhes, he was a member of the Society of Haute-Auvergne, when it was founded in 1898.
- "Bernard Brunhes, Directeur de l’Observatoire du Puy-de-Dôme (1900–1910)", Observatoire de Physique du Globe de Clermont-Fd.
- Mitchell, Alanna (2018) The Spinning Magnet: The Electromagnetic Force That Created the Modern World--and Could Destroy It