Letter, from Isaac Barrow to John Collins, dated at Trinity College Cambridge Sends Collins parts of his lectures on optics to collate together. [Note this would become Barrow's Lectiones Opticae & Geometricae (1669;1674;1685)] Will soon send manuscript "methods of calculating the dimensions of magnitudes & that of Mercator concerning the hyperbola ... as also of resolving equations" from "a friend of mine here" [Isaac Newton]. Postscriptum notes that Barrow refuses to benefit financially from printing the optics, and has refused a considerable sum of money for it but expects [bookseller Octavian] Pulleyn to "observe conditions" to expedite the printing. Annotated at the back in different hand: "Manuscripts sent to Collins by Mr Barrow July 20 1669" and top right corner "N.1 p.65. Commerc. Epist. Edit 1722" followed by "578". Numbered 1 in ink likely by Collins. Last paragraph referring to Newton printed as letter no.1, unpaginated B in first edition (1712) of Commercium Epistolicum and p. 65 of second edition (1722) 20 July 1669