302 Mr. E. W. Gudger on the 



the accounts from the old writers given in the first part of 

 this paper, and there can be no doubt that their phenomena 

 were bona fide occurrences of dead-water. One cannot 

 wonder then that when a ship was thus checked and an 

 Echeneis found, as it was not unlikely to be, sticking to 

 rudder or hull, that the fish was deemed the cause of the 

 checking of the speed of the vessel, and that the myth grew 

 and became widespread. 



Thus far we have been occupied with Ekman's accounts 

 of dead-water, now let us consider his explanation of this 

 strange phenomenon. After a study of some 42 accounts 

 and descriptions, foreign and domestic, he generalizes as 



follows : " I conclude that dead-water may occur in 



every place where fresh water flows out over the sea, but 

 that for some reason or other it is comparatively seldom 

 met with beyond Scandanavia or appears in a less decided 



manner than in the Norwegian fjords Dead-water 



only appears near to coasts, in those places where a suitable 

 layer of fresh or brackish water rests upon the heavier sea- 

 water. A vessel, moving in such a place at slight or 

 moderate speed, may happen to feel the influence of this 

 phenomenon ; it is then said that the vessel has ' taken 

 dead-water/ or f got into dead-water.' It is a very trouble- 

 some matter indeed. A sailing vessel in this plight generally 

 refuses to answer her helm and becomes unmanageable ; 

 steamers, at times sailing vessels also, keep their steerage, 

 but nevertheless the dead-water is a great hindrance, causing 

 the ship to lose her speed almost entirely. The ' Fram,' for 

 instance, so generally capable of making 4*5 knots along the 

 Siberian coast when heavily loaded, had her speed reduced 

 to about one knot in dead-water." 



Dead-water then appears to be due to a layer of fresh or 

 brackish water resting upon the heavier sea-water. The 

 greater the difference between the densities of the two layers 

 of water, the stronger of the dead-water. A vessel sailing 

 into such an area loses " way," refuses to obey her helm, 

 and becomes unmanageable ; even steamers have difficulty 

 in maintaining speed, slow ones being greatly checked and 

 at times brought almost to a standstill, while sailing-vessels 

 may he completely stopped. This appears to be due to the 

 fact that ei . . . . the vessel when moving at slow speeds 

 generated large waves in the salt-water fresh-water boundary, 

 and the resistance of these speeds was anomalously increased. 

 At higher speeds, however, the waves disappeared and the 

 resistance was not affected by the fresh-water layer." 



Ekman tried many experiments in a large glass tank con- 



