The collection comprises a large series of observations, calculations, computations and tables, with accounts, booklets, illustrations, journals of voyages, notes, treatises and other material. There is a large volume of correspondence, which reflects the varied nature of the Astronomer Royal's work, and includes correspondence with computers and comparers; letters from Gauss, Piazzi, Zach and Olbers, who contacted Maskelyne at the time of the discovery of the minor planets; and correspondence with Charles Mason about the 1769 transit of Venus. The subjects covered in the collection include marine chronometers and mathematical astronomy, the Schielhallion Experiment, Maskelyne's early life, and Charles Mason's calculation of the Moon's place. The papers are mainly in English, with other languages featuring intermittently.