Antoine Joseph Bernard Brunhes (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.
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.
He was correct, though it took another 50 years before his theory was fully accepted by the scientific community.