The jurist, mathematician, geometer and physicist Claude Mydorge (1585–1647) was fortunate to be born into a wealthy family: his father, Jean, was a councillor at the Parlement and a judge in the Grand Chamber, while his mother belonged to the Lamoignon family, one of the richest in France. Their son Claude was therefore soon appointed to a councillor’s post at the Châtelet. But rather than becoming a parliamentarian, he preferred to acquire the office of treasurer of the “généralité of Amiens”, which covered present-day Picardy. A généralité was then an administrative unit under the authority of a general collector—hence the name “généralité”—to whom, from 1577 onwards, a treasurer had been added; this largely honorary office was far from demanding. Claude Mydorge was thus able to devote most of his time, as he wished, to the study of science.
-
A mysterious acronym ----------------------
Mydorge lost no time in studying geometry and physics, taking a particular interest in optics, from which he drew a whole series of results on conic sections. This work is presented in his 1631 book Prodromi catoptricorum et dioptricorum sive Conicorum operis ad abdita radii reflexi et refracti mysteria praevii et facem praeferentis, whose title clearly refers to the cone (conicorum) and to the laws of reflection (reflexi) and refraction (refracti). In it, the author simplifies a large number of Apollonius of Perga’s proofs while developing powerful new ideas, notably introducing the notion of the “deformation of a figure”. For example, he shows how to deform a circle into an ellipse, among other results concerning the deformation of conic sections.
His technique would later be taken up by Philippe de La Hire and Isaac Newton and, later still, by Jean-Victor Poncelet (1788–1867) and Michel Chasles (1793–1880). The latter, incidentally, did not conceal his admiration for his predecessor. In his Aperçu historique sur l’origine et le développement des méthodes en géométrie, published in 1837, he writes: «Mydorge’s principal aim was not, as it was for Desargues and Pascal, to derive the properties of conics from those of the circle by perspective or by constant consideration of the cone from which they arise. His work is written in the style of the Ancients; nevertheless, by making greater use than they did of the consideration of the cone, the author can include in a single proof propositions that required three proofs in Apollonius, and thus brings great simplification to this subject.»