Jean de Beaugrand

Jean de Beaugrand , known as Géostaticien (born with Mulhouse in 1584 - died in Paris in 1640), mathematician, philosopher and engraver French, is especially known for the quarrels which opposed it to Girard Desargues (on the prospect) then with Rene Descartes (that he showed to have plagiarized Thomas Harriot in algebra).

Jean de Beaugrand was established with Paris as painter perspector in 1581, and passed the remainder of his life there. He was one of the largest specialists in the Linéographie of the XVIIe century.

He studied the algebra under the direction of François Viète, and was in correspondence with Galileo, Fermat, and of course Mersenne. He tested with a debatable success with the natural Philosophie with his test entitled “ Geostatique ” (1636), which formulated the law of variation of the weight of the bodies. Here this thesis, stated by the Mersenne Father:

… a heavy body, for example a lead bullet of a book, becomes all the more light as it approaches the center of the Earth, and it does not weigh almost anything any more when it joint to that the center, like conclud Mr. de Beaugrand in his Geostatics, where he holds that gravity of each body decreases in mesme reason which he more approaches the center of the Earth, and which mesme all the Earth does not weigh.

Descartes turned into ridiculous this thesis and concludes:

Although I aye considering much of quadratures of the circle, mouvemens perpetual, and other such alleged demonstrations which étoient false, I then however to say with truth that I ay never considering so much of errors united together in only one proposal… Thus I then to say for conclusion which all that this book of Geostatics contains is so impertinent, if ridiculous and if méprisable, that I estonne that aucuns honnestes people ayent ever condescended to take the trouble to read it, and I aurois shame of that which I ay taken to put icy of it my feeling, if I it worts do not do with vostre reprimand.

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