Descartes, 'Recueil du Calcul qui sert à la géometrie'; Sluse, 'De Inventione mediarum inter externas datas'; 'Anderso: Secti: Ang: Theor: 9 et Problena No. 1' [i.e., extract from Anderson's 1615 edition of Viète, Ad Angularum Sectionem Analytica Theoremata F. Vieta].
'Hoc scripsi Anno Dom[ini] 1650 R. T. [followed by a flourish]' written on the front cover; 'ὅσον τό xένον [sic]' added, perhaps in a different hand. Note on inside front cover, 'Ce Tretté est de M[onsieu]r René Descartes'; below, in another hand, 'To M[istr]ess Mildmay at Amersden in Oxfordshire for Mr Ash', with instructions for carriage from London. Note on inside back cover, 'Posteriorum ipsimet transcripsi en [?]originalis Auctorisamici mei amantissimi Renati Francisci Slusii. [Word lost at end]'. Pen scribbles, algebraic notes and 'fiat voluntas' in pen on back cover.