The following is the entry for Alexander Thomas Emeric Vidal in William O'Byrnes 1849 'Naval Biographical Dictionary'.
VIDAL. (Captain, 1825. f-p., 26; h-p., 18.)Alexander Thomas Emeric Vidal is brother of Commander Rich. Emeric Vidal, R.N.; and of Emeric Essex Vidal, Esq., Purser and Paymaster R.N. (1808). His father was Secretary to Admirals Sir John Lockhart Ross, Duff, and Kingsmill.
This officer entered the Navy, 1 Dec. 1803, as Fst.-cl. Vol., on board the Illustrious 74, Capts. Sir Chas. Hamilton, Michael Seymour, and Wm. Shield, with whom he served in the Channel, on the north coast of Spain, and in the West Indies, until Nov. 1805. On 22 May, 1807, he joined the Royal Naval College; and on leaving that institution he was received, in Nov. 1809, on board the Lavinia 40, Capts. Lord Wm. Stuart and Geo. Digby; in which ship we find him for upwards of three years employed on the Mediterranean, West India, Cadiz, and Lisbon stations, the chief part of the time in the capacity of Midshipman. In the course of 1813-14 he was received in succession, on the Home station, on board the Salvador del Mundo, flag-ship of Sir Robt. Calder, Niobe 40, Capt. Wm. Augustus Montagu, Cornwall 74, Capt. Edw. W. C. R. Owen, Namur 74, bearing the flag of Sir Thos. Williams, Bann 20 and Conway 24, both commanded by Capt. John Tancock, and Niobe again, Capt. Henry Colins Deacon. Sailing in the latter ship for the Halifax station, he was there, and on the Canadian lakes, employed, from Feb. to Nov. 1815, principally on Surveying-service, although for a short time as Acting-Flag-Lieutenant to Commodore Sir Edw. W.C.R. Owen. He was then presented with a commission bearing date 6 Feb. 1815. He was next, 25 Aug. 1818, appointed to the Leven 24, Capts. David Ewen Bartholomew and Wm. Fitzwilliam Owen, fitting for a surveying expedition to the coast of Africa, where he was promoted, 15 May, 1823, to the command of the Barracouta 10, also a surveying-vessel. He was advanced to Post-rank 4 Oct. 1825; and was afterwards employed, still on Surveying-service – for a short time in 1831, in the Pike 12 – from 15 Sept. 1835 until the close of 1838, and from 15 Sept. 1841 until Jan. 1845, on the coast of Africa and among the Azores, in the Aetna and Styx – and, from 7 Jan. 1845 until the early part of 1846, with his name on the books of the William and Mary yacht.
In addition to other charts, Capt. Vidal has published, under the authority of the Lords of the Admiralty, one of the Salvage Islands, with a plan of the great Salvage; 13 of the Cape de Verde Islands; one of the coast of England; and one of Vidal Bank, on the north-west coast of England. He married, in Oct. 1839, Sarah Antoinette, daughter of Henry Veicht, Esq., of Madeira, and niece of Colonel Tweedy, of Bromley House, Kent, by whom, who died in June, 1843, he has issue.