Extract, 'An answer to Monsieur Huygens etc' by [James] Gregorie An extract of Gregorie's letter to the publisher in which he comments on a letter published by Huygens regarding true circles and squares of hyperbolas. A copy of this letter is also found at CLP/1/31. Subject: Mathematics Published in Philosophical Transactions as 'An extract of a letter of Mr. James Gregory to the publisher, containing some considerations of his, upon M. Hugens his letter, printed in vindication of his examen of the book, entitled Vera Circuli & Hyperbola Quadratura'. [1660s]