The book is paginated from the end in the manner of an Oriental book, and is written from both ends. pp. 212-364 are blank. pp. 1-23 and 568-438 contain notes on the versions of the Bible (including ‘Errata Biblica’, ‘Evangelia Arabica, secundum dies festos Ecclesiæ’, etc.) in Hebrew, Samaritan, Syriac, Arabic and Ethiopian characters, with Latin renderings, etc. The remainder of the book is almost entirely filled with copies of letters, chiefly written in cypher, including Castell’s correspondence with the principal Orientalists of the day, and various persons in England. p. 404 is a letter of introduction to J. Golius given by Cæsar Calandrinus to Castell; the alternate pages from 189 to 201 have Arabic and Syriac written on them; pp. 122-129 contain the confession of the Syrian Jacobites, transcribed by order of their Metropolitan for Is. Basirius, 2 March 1653, in Syriac, with a Latin version; pp. 273 sqq contain a letter from Mr Waterhouse to Mr S. Adams, requesting his aid to relieve Castell from pecuniary difficulties; p. 39 contains a Grace passed by the Senate, 25 June 1658, ‘granting the use of Bedwell’s MS Lexicon to Edmund Castel and Richard Clark, for 2 years (on consideration for a bond of £1000), to be used for the Lexicon πολύγλωττον which they are preparing’, and which was afterwards published, London, 1669. The letters are in Castell’s handwriting, and most of them are signed ‘E. C.’. See also MSS Dd.06.63, Dd.11.39 and Dd.12.15.