physician, chemist, and inventor who devised the electromagnetic repeater for relaying telegraphic (telegraph) signals and invented an electrochemical telegraph (1838).

Davy, who wrote an Experimental Guide to Chemistry (1836), emigrated in 1839 to Australia, where, in addition to practicing medicine, he worked as an editor, farmer, and factory manager. Before leaving Great Britain he sold the patent for his telegraph; the purchasers never exploited the invention commercially, and for several decades Davy's contributions were ignored. He developed the electromagnetic repeater, which consisted of a relay to pick up and magnify electrical signals, in about 1836.