Ettrick William Creak
Captain Ettrick William Creak (1835- )
1920 Obituary [1]
APTAIN ETTRICK WILLIAM CREAK, R.N., C.B., F.R.S., was born on the 28th May, 1835, being the son of the late Commander William Creak, R.N., and a nephew of Sir H. Havelock of Lucknow fame.
He joined the Navy at the age of 14, and served on board H.M.S. "Esk" from 1863 to 1867 on the Australian station. The great range of magnetic latitude traversed during the comrnission turned Lieutenant Creak's attention to an investigation of the errors of the compass arising from that cause. This was the beginning of his researches in the Science of magnetism, and led to his appointment as an Assistant in the Compass Department of the Admiralty in 1868.
In connection with the famous "Challenger" Expedition of 1872-6 he took an active part in the determination and control of the constants required for the reduction of the magnetic observations to be made during the voyage. To him was entrusted the instruction of officers engaged in the Arctic Expedition of 1875, and the preparation of the directions and magnetic charts for the Arctic Manual. He also drew up the Magnetic Instructions for the Antarctic Expedition of 1901.
For some years before Commander Creak's appointment as Superintendent of the Compass Department in 1887 the necessity for a compass better suited to modern ships than the existing Admiralty standard had been recognized. Sir William Thomson (Lord Kelvin) had already introduced his well-known compass, fulfilling all requirements except the one essential to ships of war, namely, ability to withstand the shock of heavy gun-fire in large ships and the effect of vibration and rapid motion in small vessels such as torpedo boats and destroyers.
Captain Creak was confident that the solution of the problem lay in the development of the liquid compass and set himself to attain that object. The existing liquid compasses were far from being reliable instruments. The cards were floatless, with large moments of inertia and the weight resting upon the pivot was excessive, necessitating powerful needles with large magnetic moments in order to overcome the sluggishness resulting from the inertia, skin friction of the liquid, and the friction between the cap and pivot. He introduced cards mounted on a float, with two thin and relatively short needles fitted with their poles at the scientifically correct angular distances, and with the centre of gravity, centre of buoyancy and the point of suspension in correct relation to each other. The flotation and the total weight were so adjusted to one another as to reduce the weight resting on the pivot to a reasonable amount, and at the same time sufficient to prevent the card from jumping when subjected to vertical shocks or vibration. He was thus able to use iridium-pointed pivots instead of the relatively blunt ruby-pointed pivots which had hitherto been used. An improved form of azimuth circle was introduced at the same time. The compass thus designed rectified the defect of the Admiralty standard compass with the additional advantage of considerable steadiness under heavy gun-fire and in a seaway.
Notwithstanding this great improvement, as a manoeuvring compass it was inferior to Lord Kelvin's, owing to comparative sluggishness on a large alteration of course, through the drag on the card by the liquid in which it floated, and solely on that account, in 1892, the Admiralty adopted the Kelvin compass for the use of the Fleet.
Some years later, Messrs. E. Dent & Co. constructed a liquid compass for use by submarines, with a slightly reduced diameter of card and projecting lubber point. It was at once observed that this small alteration removed the sluggishness hitherto noticeable and rendered the instrument equal to the Kelvin compass for manoeuvring purposes, whilst retaining its superiority in other respects. The triumph of the liquid compass was now therefore complete, and in 1908 it was adopted for general use in the Navy under the name of the "Chetwynd compass."
For his various contributions to Magnetism, Captain Creak was elected a Fellow of the Royal Society in 1885, and served on the Council from 1898 to 1900. From time to time papers were read by him at the Royal Society on subjects connected with magnetism on board H.M. ships, and the discussion of the results of magnetic observations made in the course of voyages by H.M. surveying vessels and scientific expeditions.
A simple form of instrument for the correction of heeling error by magnets and the determination of vertical force both afloat and ashore was devised by Captain Creak, and he also invented the Lloyd-Creak dip and intensity apparatus. He was the author of the article on "Compasses" in the tenth edition of the "Encyclopaedia Britannica," and other publications.
Shortly before his retirement from the Compass Department in 1901 the honour of C.B. was conferred upon him. In 1903, in his Presidential address to the Geographical Section of the British Association, he gave an interesting account of our knowledge of magnetism both afloat and ashore up to that date. He was the most modest and unselfish of men, a staunch friend and full of charity to all. High minded, straightforward and true to the core, he died in his sleep on the 3rd April, 1920, in his eighty-fifth year, regretted by all who knew him.
He was elected a Member of the Institution in 1890.