Preface. 



For nearly a generation Swedish philosophers have instituted inquiries 

 into the hydrography of the Skagerak, Cattegat and Baltic i. These in- 

 vestigations have led to astonishingh' interesting results. They have suc- 

 ceeded in making the complicated currents of the Scandinavian coastal 

 waters amenable to clear understanding, in indicating their dependence 

 on wind and weather, in confirming their influence on the climate of the 

 Scandinavian countries, and during late years it has even been discovered 

 that there are definite dependent relations between the ocean currents and 

 the living organisms of the Deep, especially in respect to the migratory 

 fishes. 



Both on account of their striking results, as well as from the admirable 

 methods of work employed, these investigations promised great results in 

 the future, and, consequently, in 1893, international co-operative action 

 was arranged on the part of England, Norway, Sweden, Denmark and 

 Germany. 



At the instigation of the Swedish philosophers, this joint work was 

 undertaken with a view to investigate the waters from the Shetland 

 Islands, and up the Baltic at various seasons of the 3^ear, in the hopes of 

 placing the most important conditions of the currents of this area of sea, 

 and their periodical changes, on an established footing. 



On the part of Norwa}-, the work was entrusted to the Author by 

 the Home Department in his position as Stipendiate of State Fisheries. I 

 have, therefore, since November 1893, so far as circumstances have per- 

 mitted, made investigations in respect to the Southern and Western Shores 

 of Norway, and it has, invariably, been my object to carry out these re- 

 searches, so far as was possible, in conformity with those carried 

 on in other countries. The work has been mainly carried out in two 

 directions, pardy with attention directed to the currents per se., and 



1 See Otto Pettersson: »A Review of Swedish Hytlrographic Research in the Baltic and 

 North Seas.« Scottish Geographical Magazine 1894. 



Vid.-Selsk. Skrifter. M.-N. Kl. 1895. No. 9. 1 



