The Clavis Mathematicae (The Key to Mathematics) [Guilelmi Oughtred Aetonensis, Quondam Collegii Regalis In Cantabrigia Socii, Clavis Mathematicae Denvo Limata, Sive potius Fabricata. Cum aliis quibusdam ejusdem Commentationibus, quae in sequenti pagina recensentur. Edito tertia auctior & emendatior.] [and other titles]

The Clavis Mathematicae (The Key to Mathematics) by William Oughtred. Edition of 1652, with introduction by John Wallis. An important seventeenth mathematical treatise by the inventor of the slide rule and developer of several mathematical symbols and norms. Contains a survey of the state of mathematics in his time, as well as commentary and formulae on Euclid, Archimedes, movement of the sun and more. Complete in 8 sections, with several title pages, as originally published, each dated 1652. Guilelmi Oughtred Aetonensis, Quondam Collegii Regalis In Cantabrigia Socii, Clavis Mathematicae Denvo Limata, Sive potius Fabricata. Cum aliis quibusdam ejusdem Commentationibus, quae in sequenti pagina recensentur. Edito tertia auctior & emendatior. Oxoniae, Excudebat Leon. Lichfield, Veneunt Apud Tho. Robinson. 1652. Table of contents shows 8 sections to the book, many of which have their own title pages, as followd: [14] + 152 pages. Header is “Clavis Mathematicae / denuo limata” up through page 109. Then, “de Aequationum / Affectarum Resolutione” from page 110-151. Verso of page 151 in blank. The next page is another title page. * Elementi Decimi Euclidis Declaratio. Necnon De Solidis Regularibus Tractatus. Authore Guilelmo Oughtred Anglo Oxoniae, Excudebat Leon. Lichfield, Veneunt Apud Tho. Robinson. Anno Dom. 1652. Header reads “Elementi Decimi / Euclidis declaratio” from pages 1-29. Header is “De solidis Regularibis” for 30-46. The next page is another title page. * Theorematum In Libris Archimedes De Sphaera & Cylindro Declaratio. [same author, printer & date] pages numbered [2] + 10. Then another title page. * Horologiorum Sciotericorum In plano Geometrice solum, sine Calculo Trigonometrico, delineandorum, Modus Facillimus. Per quem Meridiana, Substylaris, & Stylus Ipse, non investigantur modo, sed Etiam, in cujusuis generis Plano, situ Proprio inscribuntur, omniaque Perspicue demonstrantur Inventore Guilelmo Oughtred 23um Aetatis Annum Agente. [same publisher and date] pages numbered 1-41 (although several pages are not numbered or mis-numbered). Page 41 ends with “Finis” and the verso of that page is blank. The next page is blank as well, but the verso of that page (the last page present) has 3 figures on it, with notes that refer to other figures in the text. “Haec figura ita abtanda est figurae pag. 40…” According to the pagination of a copy that sold at Sotheby’s in 2004, there should be one more page of diagrams at the end, lacking in this volume. William Oughtred (1574-1660) was a English mathematician who is credited with the invention of the slide rule. It was Oughtred who introduced the symbol ‘x’ indicate multiplication, as well as ‘sin’ and ‘cos’ abbreviations. The Clavis Mathematicae (The Key to Mathematics) was first published in 1631. It includes a descriptions of alternate mathematical notations, as well as decimal fractions and algebra. Oughtred’s preference for a symbolic language of mathematics is laid out; His use of the ‘x’ symbol for multiplication, the ‘::’ for proportion and sin/cos for those functions have been universally adopted. The book was reprinted in 1647 in English and in 1648, 1652, 1667 & 1693 in the original Latin. This copy retains original leather spine, but text block is split in 2 pieces at page 82/83. Front blank detached but present. No covers attached to the text block. One cover present (appears to be rear cover). Title page toned and chipped at the edges. Dozens of diagrams and tables and mathematical equations throughout. Text in Latin. Measures 4” x 6”.