He was born at Tadlow, in Cambridgeshire. At the age of fifteen he entered Emmanuel College, Cambridge, but afterwards moved to St John's, because of the valuable library there. His great work, the Lexicon Heptaglotton Hebraicum, Chaldaicum, Syriacum, Samaritanum, Aethiopicum, Arabicum, et Persicum (1669), took him eighteen years, working (according to his own account) from sixteen to eighteen hours a day; he employed fourteen assistants, and spent £12,000, ruining himself in the process, there being little demand for his finished lexicon.
By 1667, he was in prison because he was unable to discharge his brother's debts, for which he had made himself liable. However, a volume of poems dedicated to the king brought him preferment. He was made prebendary of Canterbury Cathedral and professor of Arabic at Cambridge. Before undertaking the Lexicon Heptaglotton, Castell had helped Dr Brian Walton in the preparation of his Polyglott Bible. He died at Higham Gobion, Bedfordshire, where he was rector, and bequeathed his manuscripts to the University of Cambridge.
The Syriac section of the Lexicon was issued separately at Göttingen in 1788 by J D Michaelis, who made a tribute to Castell's learning and industry. Trier published the Hebrew section in 1790-1792.
This entry was originally from the 1911 Encyclopedia Britannica.