30 EKMAN. ON DEAD-WATER. [NORW. POL. EXP. 



the only way being to reverse the engine and go astern. I found, myself, great difficulty 

 in steering when going slow and at all across the current. With the ship stopped across 

 the current, the water would be seen making past the bow and stern down river at a con- 

 siderable rate, giving the appearance of the ship drifting headside on against the current. 

 On making some rather detailed observations, the reason of this became apparent. The 

 fresh water of the Congo running at 3 or 4 knots, on meeting the salt water of the sea 

 some miles inside the actual mouth, passes over it with increased velocity — 5 or 6 knots 



— and diminished depth, in some cases only a few feet, the salt water below having only 

 a faint tidal motion, so that a vessel's keel may be in still water and her water line in a 

 current ot 5 or 6 knots, which amply accounts for the difficulty experienced." 



No. 40. M. Dechaille, "directeur des signaux de sauvetage", Havre, has 



— in "Journal de Havre" — given the following particulars of a phenomenon, 

 known at the mouth of the Loire, by the name of "les bournes". 



"When a vessel is influenced by this phenomenon, it is said that "le navire est em- 

 bourne"; she then does not answer her helm until she has got out of the region of the 

 phenomenon. 



"Once, I was in command of a 600 ton sailing-ship and had left Nantes with a good 

 easterly breeze, able to give the ship a speed of 6 knots. At the mouth of the Loire the 

 ship became "embourne" and turned all round two or three times. I succeded in coming 

 out of the "bourne", and then my ship again answered her helm and sailed without any 

 further accident. I do not believe that the "bourne" would have had any effect on a big- 

 ger ship, and not at all on a steamer." 



An old pilot says about this phenomenon, that it effects vessels at even a velocity of 

 5 or 6 knots, and even large steamers. He has not observed it except after heavy rains, 

 or when the snow has been melting, or when the Loire rises above its banks after a series 

 of storms. 



No. 41. Mr. F. Picamilh, Bordeaux, has kindly sent me the following 

 information respecting the river Garonne, in the neighbourhood of Bordeaux. 



"The river is always very muddy, so that objects left on the shore during one high 

 tide may become covered with several millimetres of mud. In the summer, which is the 

 dry season, the water in the river is considerably reduced, and its level sinks. Then the 

 rising tide stirs up enormous quantities of the deposits from the bottom, giving to the 

 river the appearance of a river of mud. 



"Seamen then say: "les eaux sont lourdes". Vessels steer with difficulty; but more 

 particularly lighters cannot navigate the river in the usual way by the help ot the current. 



"For navigating the river, these lighters, having an anchor dragging at the bottom, 

 are left to drift with the current. If the vessel should be moved in a direction different 

 to that of the current, she is made to swing out by the help of the rudder, as indicated 

 by Fig. 2. But when "les eaux sont lourdes" it is, sometimes, impossible to perform this 

 manoeuvre: The lighter does not answer her helm, and in spite of a strong current im- 

 pelling the rudder, she remains immovable in the direction of the cable (Fig. 3)." 



No. 42. Mr. Picamilh has told me of another peculiarity experienced in 

 the basin at Arcachon west of Bordeaux. 



"This basin is filled with sand-banks, which during the high tide under water, are at 

 low tide above the water-level, and are separated by deep, navigable channels. The water 

 in the basin is pure Atlantic water, and the rivers disemboguing there, carry but little water. 



