DEAD WATER.

"Dead water" is something different from water that is devoid of current. Dr Nansen's Norwegian North Polar expedition has been responsible for the throwing of a good deal of light on the subject. On August 29, 1893, the Fram was steaming m smooth and open water between the Isle of Taimur and Alonquist Islands, and towards evening approached thick ice to make fast to it. A very slow current was observed as she neared the ice, but the vessel made extremely slow progress, and the speed was reduced to one of one and a-half knots, although the engines were working at full power, which would have given her a speed of from four and ahalf knots to five knots under ordinary ci) cumstances. Nansen's Journal attributed this singular behaviour to the Fißin having "got into dead water." Professor Bjerknes, consulted by Nansen m 1898, suggested as explanation of the occurrence that "m the case of a layer of fresh water resting on the top of salt water a ship will not only produce the ordinary waves at the boundary between the air and the water, but will also generate invisible waves m the boundary be tween salt water and fresh water— the great resistance experienced by the ship being due to the work done m generating these invisible waves." The task of making a rigorous experimental investigation on the subject was taken up by Dr Ekman (assistant m the Central Laboratory for the International Study of the Sea at Christiania) whose memoir on tlie subject is a valuable contribution to scientific literature. It is demonstrative that Professor Bjerknes's suggestion furnishes a reasonable explanation of the phenomenon of dead water. A groat body of testimony regarding this phenomenon is brought together from logs, journals, letters of experienced seamen, and so forth, all comprising the observation made by Nansen m the Fram, that ships encountering a layer of fresh or brackish water superposed on sea water of greater density experience a greatly increased resistance, loss m speed, and not infrequently become unhandy, not answering their helm. These results obtain when vessels are moving at very low speeds on their getting into dead water. They are much more frequently seen m sailing vessels than m steamers, and occur m the estuaries of rivers, straits, fiords, or other situations where fresh water accumulates. Any change m the condition of the surrounding water, such as the passage of another vessel near the ship "m dead water," or a sudden alteration m the speed of a ship, tends to destroy the drag of the dead water and to set the vessel free. Steamships possessing capacity for high speed may get into dead water when moving very slowly, but have no difficulty m freeing themselves by using their engine power m resei ye. Sometimes when dead water is encountered there is a considerable current on the surface, (sometimes again there is none.