NO. is.] COLLECTIVE DESCRIPTION. 



the former has mingled with the latter. In one of the strongest cases of 

 dead-water that we know of — the experience of the Fram at Taimur — 

 this difference of density was about as great as possible (fresh drinking water 

 on the sea-surface, and pure sea-water on a" level with the bottom-cock of 

 the engine-room). In the Norwegian fjords, where the conditions are unusually 

 good for river-water spreading almost unmixed over pure sea-water, most 

 marked cases of dead-water are quite general. In the Kattegat, the density 

 of the sea-water is not so great, and the river-water, before flowing out over 

 the sea, becomes much mixed with sea-water. Dead-water appears there only 

 with a light breeze, after some days of fine weather, and not at all when the 

 water-layers are stirred by previous storms. (In the neighbourhood of the 

 mouth of the G5ta River, however, strong dead-water has been experienced). 

 In the Baltic, where the specific gravity is less than 1'006 or 1'007, dead- 

 water is only exceptionally observed, and then only with very feeble wind. 



Furthermore, the relation between the thickness of the surface-layer 

 and the draught of the vessel is of great importance as regards the effect 

 of dead-water. At the mouth of the Glommen, for instance, small craft 

 experience dead-water farther out at sea, where the surface-layer has less 

 thickness, than large vessels, by which it is again felt higher up the river (see 

 Account No. 3). According as the outflow of fresh water increases, the region 

 where dead-water appears withdraws from the river mouths seawards, and vice 

 versa. In winter, when there is little water in the Glommen, dead-water prin- 

 cipally appears in the river proper, between the town and the Sarp rapids 

 (see the maps, PI. Ill); but in summer its region is below the town and ex- 

 tends as far as the outermost rocks of the Kristiania Fjord. 



Another fact, probably connected with the one stated above, is that dead- 

 water is generally stronger in a moderate sea-breeze, than when a land- 

 breeze is blowing. For, as a result of the sea-breeze, the fresh water is 

 retained at the coast and its depth becomes in concequence greater, while 

 the land-breeze carries most of it out to sea. On the Glommen the dead- 

 water is said to be stronger at flood-tide, than at ebb — possibly owing to 

 the tidal currents or to variations in the depth of the fresh-water layer. 



Some of the narrators attribute importance to the shape of the vessel: 

 it is said that a sharp built vessel is more exposed to dead-water than one 



