14 JOHAN HJORT. M.-N. Kl. 



sailors. Against a contrary S. W. wind thej'^ can, when tacking under 

 reefed sails, get from Færder to Oxø, Lindesnæs and Lister.« 



In the depths below this current we discover the in-going laj-ers. 

 One can with Pettersson and Ekman^ distinguish several such layers: — 



1. The Ocean Water, the Atlantic Water wiüi a salineness of more 

 than 35 per looo. This has a similar amount of saline contents 

 as the Adantic, and covers the bottom of the Skagerak in one great 

 layer. 



2. The North Sea Water; saline contents 35 to 34 per 1000. In the 

 Skagerak this forms the layer above the Adantic Water, and in the 

 North Sea is on the surface. 



3. The Bank Waters or mixed layers; saline contents 34 to 33 per 

 1000, and 33 to 32 per 1000, which lie immediately below the Baltic 

 Current, and during the Autumn rise to the surface, as a rule, on 

 the Norwegian Banks, and invariably on those off the West Coasf^of 

 Denmark. 



These various layers possess, not only their characteristic saline 

 contents, but, likewise, many other characteristic features. Thus each 

 laver owns a certain — or tollerabh^ certain — amount of carbonic acid 

 and oxygen, and what is of greatest importance is that each layer at 

 various seasons has a certain temperature of its own. hi Summer, for in- 

 stance, the Baltic Current is warmer than the other layers, as it runs from 

 the warmer regions of the East. In the Winter, on the other hand, the 

 conditions change, as the water of the current is then colder by far than 

 that of the open sea, because it obtains such an addition of ice water. The 

 Atlantic Water is at the same time xcvy warm, as well as the other 

 layers, even if to a less degree. 



It would occupy too much space here to state even the most im- 

 portant of all the interesting and important results obtained by the 

 Swedish scientists, and I shall confine myself to reverting to them in the 

 following chapters. 



What is of greatest importance here is, that Pettersson and Ekman ^ 

 have discovered that the Herring Fishery, off Bohuslän, is entirely depen- 



» Grunddrageu af Skageracks och Kattegats hydrografi. (Outlines of the Hydrography 

 of the Skagerak and Cattegat.) K. s. vet. handl. bd. XXIV no. ii. Stockholm 1891. 



•- Om det hydrografiska tilståndet i Bohusläns skargård vid tiden for vinter-sillfiskets 

 upphörande 1878, i8qo och I891. (Concerning the Hydrographie Conditions in the 

 Archipelago or Island Belt of the Bohuslän previous to the close of the Winter Her- 

 ring Fisher^s 1878, 1890 and 1891). Overs, k. vet. aks. forhandl. 1S91. No. 7- 

 Also »Grunddragen af Skageracks och Kattegats hydrografi (loc. cit.).« (Outlines of 

 the Hydrography of the Skagerak and Cattegat). 



