William Hewett

William Hewett was a Royal Navy officer noted for making the first comprehensive survey of the North Sea and for his work on tides. Hewett went to sea in first in the war with France, from 1805 to 1811, and in China in 1811. He then joined as midshipman. From 1813 he served in , and carried out a number of surveys on the coast of Brazil, including Maranhão, Ceará and Bahia. He was made an acting Lieutenant in 1814, which was confirmed in 1815. Hewett's first command was the surveying vessel HMS Protector. From 1818 to 1830 he carried out surveys of the east coast of England, an area noted for dangerous and often shifting shoals. Hewett's description of the Leman and Ower banks, off the coast of Norfolk is given in full in the North Sea Sailing Directions of 1846. Other areas surveyed included Yarmouth Roads, the entrance to the Humber estuary, Lynn and Boston Deeps, The Gabbards and the Dudgeon. He also made recommendations for improvement of navigation of the coast, in particular regarding positioning of lighthouses and light vessels. He tested nautical inventions and trial compasses, reporting results to the Admiralty's committees. In 1830, Hewett was promoted to Commander, and in 1831 took command of HMS Fairy. He began his great work of surveying the North Sea to the Dutch coast and including the Dogger Bank. Four chronometers were supplied for determining longitude. As well as normal surveying work, Hewett was engaged to test the theory of William Whewell who had suggested that between the Suffolk and Dutch coasts there should be a point at which there would be neither rise nor fall of the tide - what is now known as an amphidromic point. This involved anchoring the ship and taking repeated soundings at the same location with lead and line, precautions being needed to allow for irregularities in the sea bed, and the effects of tidal flow. The data supported Whewell's prediction, with a rise of no more than .