[135]J. Craig, De calculo fluentium, London, 1718, p. 86.
[136]Jo. Wilson, Trigonometry, 2d ed., Edinburgh, 1724, p. v.
[137]Commercium Epistolicum, 1712, p. 20.
[138]C. Le Paige, “Sur l’origine de certains signes d’opération,” Annales de la société scientifique de Bruxelles, 16th year, 1891-92, Part II, pp. 79-82.
[139]Gravelaar, “Over den oorsprong van ons maalteeken (×),” Wiskundig Tijdschrift, 6th year. We have not had access to this article.
[140]H. Bosmans, op. cit., p. 40.
[141]Claudii Ptolemaei . . . . annotationes, Bâle, 1551. This reference is taken from the Encyclopédie des sciences mathématiques, Tome I, Vol. I, Fasc. 1, p. 40.
[142]Due Correction for Mr. Hobbes. Or Schoole Discipline, for not saying his Lessons right. In answer to his Six Lessons, directed to the Professors of Mathematicks. By the Professor of Geometry. Oxford, 1656, pp. 7, 47, 50.
[143]Oughtred, Apologeticall Epistle, p. 27.
[144]J. Edleston, Correspondence of Sir Isaac Newton and Professor Cotes, London, 1850, pp. 279-92.