• Born on April 12,1794 in Le Bourget, France
• Studied at Ghent, then in 1813 he entered the Ecole Polytechnique in Paris
• A mathematician whose career was very much influenced by the political upheavals of his time
• Began his military career in 1813 when he volunteered to fight the British
• Wounded in action in both 1814 and 1815
• During Napoleon's 100's days back in control of France, he worked under the command of another mathematician
• He worked on geometry and has an important theorem on the intersection of a cone and its inscribed sphere with a plane, discovered in 1822, named after him
• He also worked on stenographic projection, static, algebra and probability
• After the war, he returned to Belgium and continued his military career as an engineer
• In 1825, he was elected to the Royal Academy of Sciences in Brussels and for the next five years, he was a professor of mining engineering.
• Died on February 15, 1847 in Brussels, Belgium

     Dandelin Cone is the theorem that Germinal Dandelin discovered in 1822 and named after him. The theorem shows that if a cone is intersected by a plane in a conic, then the foci of the conic are the points where this plane is touched by the spheres inscribed in the cone. In 1826, he generalized his theorem to a hyperboloid of revolution, rather a cone, relating Pascal's hexagon, Brianchon's hexagon and the hexagon formed by the generators of the hyperboloid.

     Pascal's famous Mystic Hexagram Theorem states that if an arbitrary hexagon is inscribed in a conic, then the interesection points of the three pairs of the hexagon opposite sides are collinear, and conversely.

     Brianchon's Theorem states that In a hexaon circumscribing a conic section, the three opposite diagonals all intersect in a single point.