An idea of Oughtred’s influence upon mathematical thought and teaching can be obtained from the spread of his symbolism. This study indicates that the adoption was not immediate. The earliest use that we have been able to find of Oughtred’s notation for proportion, A.B::C.D, occurs nineteen years after the Clavis mathematicae of 1631. In 1650 John Kersey brought out in London an edition of Edmund Wingates’ Arithmetique made easie, in which this notation is used. After this date publications employing it became frequent, some of them being the productions of pupils of Oughtred. We have seen it in Vincent Wing (1651),[77] Seth Ward (1653),[78] John Wallis (1655),[79] in “R. B.,” a schoolmaster in Suffolk,[80] Samuel Foster (1659),[81] Jonas Moore (1660),[82] and Isaac Barrow (1657).[83] In the latter part of the seventeenth century Oughtred’s notation, A.B::C.D, became the prevalent, though not universal, notation in Great Britain. A tremendous impetus to their adoption was given by Seth Ward, Isaac Barrow, and particularly by John Wallis, who was rising to international eminence as a mathematician. In France we have noticed Oughtred’s notation for proportion in Franciscus Dulaurens (1667),[84] J. Prestet (1675),[85] R. P. Bernard Lamy (1684),[86] Ozanam (1691),[87] De l’Hospital (1696),[88] R. P. Petro Nicolas (1697).[89] In the Netherlands we have noticed it in R. P. Bernard Lamy (1680),[90] and in an anonymous work of 1690.[91] In German and Italian works of the seventeenth century we have not seen Oughtred’s notation for proportion. In England a modified notation soon sprang up in which ratio was indicated by two dots instead of a single dot, thus A:B::C:D. The reason for the change lies probably in the inclination to use the single dot to designate decimal fractions. W. W. Beman pointed out that this modified symbolism (:) for ratio is found as early as 1657 in the end of the trigonometric and logarithmic tables that were bound with Oughtred’s Trigonometria.[92] It is not probable, however, that this notation was used by Oughtred himself. The Trigonometria proper has Oughtred’s A.B::C.D throughout. Moreover, in the English edition of this trigonometry, which appeared the same year, 1657, but subsequent to the Latin edition, the passages which contained the colon as the symbol for ratio, when not omitted, are recast, and the regular Oughtredian notation is introduced. In Oughtred’s posthumous work, Opuscula mathematica hactenus inedita, 1677, the colon appears quite often but is most likely due to the editor of the book.