Alexander Thomas Emeric Vidal Alexander Thomas Emeric Vidal ( 1792 – 5 February 1863 ) was an officer of the Royal Navy . He became an accomplished surveyor , and reached the rank of vice - admiral . Early life . Vidal was born in 1792 , the youngest of four children of Emeric Vidal , who served in the Royal Navy . Alexander followed his father , embarking on a naval career in December 1803 when he joined as a 1st class volunteer . He served alternately under Sir Charles Hamilton , Michael Seymour and W . Shield . He initially served in the English Channel , off the north coast of Spain and in the West Indies , until November 1805 . He later joined the Royal Naval College at Portsmouth , before joining in November 1809 . Here he served under Lord William Stuart , and George Digby . He spent three years aboard the " Lavinia " at the rank of midshipman , and saw service in the Mediterranean and West Indies , and at Cadiz and Lisbon . Promotion . He then served on the Home Station , successively aboard , , , , and . He sailed aboard the " Conway " to the North American Station , and on arrival , spent time on the Great Lakes working in a surveying role . He was briefly employed as flag - lieutenant to Commodore Sir Edward Owen , before receiving his commission , dated February 1815 . He was appointed to in August 1818 , rising to the post of first lieutenant under William Owen . The death of Commander Cudlip led to Vidal being appointed to his first command , that of , and in May 1823 he was confirmed with promotion to the rank of Commander . He accompanied Owen on his voyage to Africa and on his return to England in October 1825 , he was promoted to post - captain . Hunt for Aitkin ' s Rock . Aitkin ' s Rock was a supposed rock in the North Atlantic . Despite being observed and named by a merchant , it had not been reliably charted , and expeditions , by in 1824 ; and in 1827 ; and and had all failed to locate it . In the summer of 1830 , the Admiralty placed Vidal in command of and and ordered him to investigate . There had been at least seven separate reports of the potential hazard , said to be small and protruding only about four feet from the water . Francis Beaufort worked out a rough position for the rock and Vidal set out to investigate . He spent six weeks charting the supposed locations and all of the positions in between , without discovering any evidence . Satisfied that the rock was a mere vigia , he returned to port . During his surveys in search of the rock , he discovered and charted Vidal bank , and the next year became the first to accurately chart and describe Rockall . African mapping . Vidal sailed aboard in December 1835 , carrying 12 chronometers . He intended to calculate the meridian arc length to the Cape Verde Islands , and the west coast of Africa . He eventually carried out detailed surveys all along the African coast , so that by 1838 the Secretary of the Royal Geographical Society could remark of the survey that This tedious undertaking is drawing to a close , and will then be of equal utility to the fair traders and the anti - slavery cruisers . It is fortunately in the hands of such a man as Captain Vidal , R . N . , who has steadily devoted himself during a long period of ill - health , to complete this unpopular work , and to connect with it a minute examination of the Canary Islands . Vidal then carried out surveys of the Azores aboard from September 1841 until January 1845 . He then moved aboard the yacht " William & Mary " to complete the work . Later life and legacy . Vidal was promoted to rear - admiral on 27 January 1851 , and vice - admiral on 17 June 1859 . He had married Sarah Antoinette , daughter of Henry Veitch , the Consul General of Madeira , in October 1839 and had two sons , Owen Alexander ( b . 1841 ) and Beaufort Henry ( b . 1842 ) . Following his wife ' s death in 1843 , Vidal emigrated to Canada , where he joined his eldest brother Richard Emeric Vidal in the founding of Sarnia , Ontario . He died at Clifton , Bristol on 5 February 1863 , aged 73 . The survey ship , launched in 1951 , was named in his honour . In 1955 a party from HMS " Vidal " were landed on Rockall to claim it as part of the United Kingdom , thus claiming the islet that Alexander Vidal had first surveyed over a hundred years before .