, an illustrious naval officer, the second son of Alexander Duncan,
, an illustrious naval officer, the second son of Alexander Duncan, esq. of Lundie, in the county of Angus, in Scotland, by Helen Haldone, daughter of Mr. Haldone, of Gleneagles in Perthshire, was born in the month of July 1731, and received the first rudiments of education at Dundee, and, appears to have been early intended for the naval service, as his elder brother Alexander was for that of the army, of which he died lieutenant-colonel in 1771. About 1746, Adam was put under the command of capt. Robert Haldane, who was then commander of the Shoreham frigate, with whom he continued two or three years. In 174y he was entered as a midshipman on board the Centurion of 50 guns, which then bore the broad pendant of commodore Keppel, who was appointed commander in chief on the Mediterranean station, for the customary period of three years. In Jan. 1755, he was promoted to the rank of lieutenant, by the recommendation of commodore Keppel, who knew his merits; and was appointed to the Norwich, a fourth rate, commanded by captain Barrington, and intended as one of the squadron which was to accompany Mr. Keppel to America, with transports and land forces under the command of general Braddock. After the arrival of this armament in Virginia, Mr. Duncan was removed into the Centurion, in which he continued until that ship returned to England, and captain Keppel, after having for a short time commanded the Swiftsure, being appointed to the Torbay of 74 guns, procured his much esteemed eleve to be appointed second lieutenant of that ship. After remaining on the home station for the space of three years, he proceeded on the expedition sent against the French settlement of Goree, on the coast of Africa. He was slightly wounded here at the attack of the fort; and soon afterwards rose to the rank of the first lieutenant of the Torbay, in which capacity he returned to England.