Edward Davy (16 June 1806 – 26 January 1885) was an English physician, scientist, and inventor who played a prominent role in the development of telegraphy, and invented an electric relay.
Davy was born in Ottery St Mary, Devonshire, England, son of Thomas Davy (medical practitioner and house surgeon at Guy's Hospital, London). Edward Davy was educated at a school run by his maternal uncle in Tower Street, London. He was then apprenticed to Dr C. Wheeler, house surgeon at St Bartholomew's Hospital. Davy won the prize for botany in 1825, was licensed by the Worshipful Society of Apothecaries in 1828 and the Royal College of Surgeons in 1829. Davy's telegraph was not protected by a patent at this stage, but one was granted in the following year, 1838, despite the objections of Cooke and Wheatstone. Davy invented a relay which used a magnetic needle which dipped into a mercury contact when an electric current passed through the surrounding coil. In recognition of this he was elected in 1885 as an honorary member of the Society of Telegraph Engineers and was informed of this by telegraph shortly before his death.
Davy's marriage broke down shortly after the Regent's Park demonstration and he found himself in litigation with his wife and her creditors. In August 1838 he fled to Australia to avoid them, giving up work on the telegraph in the process. His telegraph patents were purchased by the Electric Telegraph Company in 1847 for £600, The rest of his telegraph system was not wanted, other than to prevent competitors from using it. He was editor of the Adelaide Examiner from June to July 1842 and was elected president of the Port Adelaide Mechanics' Institute at its inaugural meeting in 1851.