Martyn started in business in 1649, in partnership with John Ridley; their shop was at the sign of the Castle in Fleet Street, near Ram Alley.
They issued all of its printed documents, including the Philosophical Transactions; they published Thomas Sprat's History of the Royal Society (1667), and Robert Hooke's Micrographia (1665).
On his own, Martyn was an accomplished publisher of law books and of texts in Latin and Greek; his edition of Thomas Blount's legal dictionary Νομο-λεχικον ("Novo-lexicon," 1671) is a noteworthy example.
[2] Martyn was responsible for a wide range of books, including the religious works that were so characteristic of his century, like Edward Wetenhall's Enter into Thy Closet, or A Method and Order for Private Devotion (1666).
He issued Francis North's A Philosophical Essay of Music and John Milton's The History of Britain, both in 1677; and he published medical works, like the London Pharmacopoeia of the Royal College of Physicians (also 1677).