My original tumblr post was here. Nyctalope, created in 1911 by the French writer Jean de la Hire (1878-1956) may be the first cyborg in literature. I have no idea what he’s up to here, though. This image was first blogged on tumblr by ronaldcmerchant and comes to us via arcaneimages.
John A. B. C. Smith from Poe’s “The Man That Was Used Up” (1839) is probably the first cyborg in literature, so the Nyctalope would probably be the first cyborg in literature to feature in books (plural), but that distinction might fall to the Tin Woodman from the Oz series (1900 onwards), who was retconned by Baum in 1904 into having been originally human.