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Admiral Sir Henry Mangles Denham (1800-1887)
1888 Obituary 
HENRY MANGLES DENHAM was born 28th August, 1800.
He entered the Navy in April, 1809, as a volunteer, on board the “Daphne,” 20, Captain Philip Ripon, on the Guernsey and Jersey station, where he served from April 1810 until May 1814, latterly as midshipman, in the “Vulture,” 10, Captains Martin White, George Norris, and Henry Baugh.
During the three following years he was borne on the books of the “Queen Charlotte,” the “Boyne,” and the “Prince,” ships-of-the-line, but detached the whole of the time on the survey of the Channel Islands, under his former commander, Captain Martin White; with whom as midshipman and lieutenant (commission dated 26th December, 1822,) of the “Shamrock,” 14, he was employed from March 1817 until May 1827 in examining the English and Irish Channels, and the south-west and north-east coasts of Ireland.
In October 1827 Mr. Denham assumed command of the “Linnet,” 10, for the purpose of surveying the coast of France; and while nominally attached, between September 1828 and March 1835, to the “St. Vincent,” the “Caledonia,” and the “San Josef,” he conducted a survey of the Bristol Channel, and of the ports of Liverpool and Milford.
He was promoted to the rank of Commander on the 20th of March 1835, and was employed from January 1842 until July 1845 in the “Lucifer,” and the “Royal Sovereign ” yacht, in defining the coasts of Lancashire and Cumberland ; was then appointed to the “Avon,” s.s., and on 27th September following sailed on surveying expedition to the coast of Guinea, including the mouth of the Niger.
He returned to England on the 17th August, 1846, and was borne on the books of the “William and Mary,” Royal yacht; from the end of December following until the summer of 1847.
From 1848 to 1851 Captain Denham was employed in conducting government inquiries into accidents at sea. In 1851 strong representations were made to Her Majesty’s government respecting the rapidly increasing traffic between the Australian colonies and the western coast of America, and the inadequate state of knowledge of the intervening navigation among the insulated rocks and intricate clusters of islands which extend to the eastward of New Caledonia. As a result of these representations an exploring and surveying expedition left England in 1852 in the “Herald,” under the command of Captain Denham. A detailed account of the work of this expedition will be found in the Proceedings of the Royal Geographical Society for 1862.
It returned to England in 1861, after nine years’ absence, and Captain Denham was thanked in the House of Commons for his great services, besides receiving the voted thanks of various colonial legislatures and other public bodies.
In 1864 he was made a Rear-Admiral, and two years later received the honour of knighthood. He was promoted to Vice-Admiral and Admiral in 1871 and 187i respectively.
He died at an advanced age on the 3rd of July, 1887.
Admiral Sir Henry Denham had long outlived the period of his active employment, entering the navy as he did but four years after the battle of Trafalgar, but his name was prominent in the middle period of the century. So much was his surveying work round the British coast esteemed that he was specially promoted to the rank of commander before he would otherwise have gained the step, "To mark the high sense entertained by my Lords of the advantages accruing to the public from the completion of his survey of the port and harbour of Liverpool and the neighbouring coast.”
He succeeded in averting the threatened return of the port of Liverpool to the mere capacity of a half-tide harbour, by harrowing a new opening through the Burbo and Jordan Sands, which, on the accession of her Majesty to the throne, was named the “Victoria Channel.” In reference to a steam survey made by him in the North Sea, the late Hydrographer of the Admiralty, Sir Francis Beaufort, declared it to be his conviction “that no man could have achieved that great work with more skill;" and in remarking upon the survey of Morecambe Bay, the same eminent authority recorded it as his opinion" that a more complete and masterly work had rarely been sent to the Admiralty office.”
In allusion to Captain Denham’s services in the "Avon,” on the coast of Africa, whither he was sent for the express purpose of surveying the Bight of Benin, the Hydrographer thus expressed himself: "In examining the survey made in such a deleterious climate, along such an impracticable coast, and in contact with such a treacherous population, I was prepared to make great allowances for work done under such striking disadvantages ; but I find, with equal pleasure and surprise, that the whole has been performed with all the precision and fulness that could have been expected if made under the most favourable circumstances.”
For this service Captain Denham was promoted to post rank. He was the inventor of “Denham Rowlocks” for rowing boats, and of "Denham’s (registered) Jury Tiller” for steering a ship on fire abaft, or, when twisting her rudder, ahead, breaking her tiller in a gale of wind, or receiving the enemy’s shot.
In 1830 he received the thanks of the Trinity Board; in 1834, he was further presented with the freedom of the borough of Liverpool, and elected a member of the Literary and Philosophical Society at that place; and in 1839 he was chosen a Fellow of the Royal Society; as likewise in 1541, a Younger Brother of the Trinity Corporation, and a member of the United States National Institution for the Advancement of Science. He received the thanks of the Geological Society, of several committees on Harbours of Refuge, and of the Committee of Lloyd‘s.
Admiral Sir Henry Denham was elected an Associate of the Institution on the 4th of March, 1851, when in the heyday of his career as a marine surveyor.