The son of Gilbert Dyer, a schoolmaster on the eastern side of Dartmoor, he was born in the hamlet of Dunstone in the parish of Widecombe-in-the-Moor, Devon, and baptised on 14 September 1743.
After working as his father's assistant, he was appointed in June 1767 master of the school at Tucker's Hall, Exeter, and was there for 21 years.
[1] About 1788 Dyer opened a bookseller's shop opposite the Guildhall in Exeter, and soon became prominent in the trade, in the west of England.
[1] Dyer published in 1796 an anonymous tract The Principles of Atheism proved to be unfounded from the Nature of Man, in which he aimed at establishing that man "must have been created, preserved, and instructed by Divine Providence".
Dyer's subsequent work Vulgar Errors, Ancient and Modern (1816)[2] contained the 1796 tract on atheism, and commentaries on Richard of Cirencester and Antoninus, which had been published in 1814.