This entry contributed by Margherita Barile

Belgian mathematician and engineer who served in the French and Belgian armies. In the Belgian army, he was in charge of building fortifications. He was only 20 years old when he was awarded the Légion d'Honneur by Lazare Carnot, who at that time was Napoleon's Minister of the Interior. In 1816, Dandelin participated in the construction of two telescopes in Namur. He entered the Royal Academy of Brussels in 1822, thanks to a brilliant geometrical work on the parabolic focal curve, where he presented a new elegant proof of a theorem found by his friend Quetelet, which characterized the foci of conic sections with the points of tangency of what are nowadays known as the Dandelin spheres.

In a curious paper that he published in 1826, Dandelin transferred the same result to the plane sections of a hyperboloid of revolution, where he also re-demonstrated the theorems of Pascal and Brianchon .

In 1825, the University of Liège assigned him a professorship for a discipline called "exploitation of mines"; the research in this area took him to Germany and England. Later he taught physics at the University of Namur. His fields of interest ranged from projective geometry and algebra to astronomy and mechanics.

Carnot (Lazare)