can only in a slight degree be caused by ttie variations in down- 

 fall from one month to another. The principal cause must be 

 looked for in another direction, and one naturally turns one's atten- 

 tion to the distribution of atmospheric pressure, which, as is well 

 known, determines the motions in the air — atmospheric currents — . 



Di-. Andreas Hansen^) has called attention to the fact that 

 the maximum atmospheric pressure in the spring and the minimum 

 height of the water, and the minimum midwinter barometric altitude 

 and the greatest height of the water are, practically speaking, 

 correspondent. 



Prof. MoHx-j in his meteorology, has given the atmospheric 

 pressure curves at Stykkisholm, in Iceland, and Gjesvær, near the 

 Noith Cape, and with respect to the course of these curves, he 

 says that, on both sides of tiie Norwegian Sea, the atmosplieric 

 prcssur'e is lowest in the winter and highest in May. 



'fhe lowest atmosphei'ic pressure from January — May, we 

 should expect to iind somewhere in the Norwegian Sea, and this 

 is seen to be the case from Mohn's chart (1. c. p. 173) where a 

 minimum is given at the NE of Iceland. This minimum is main- 

 tained, according to Prof. O. Pettersson,^) by the upper layers 

 of water in tlio Norwegian Sea giving olF heat to the atmosphere. 

 At any rate, it appears to be certain that the distribution of 

 the atmospheric pressure on land and sea during the winter causes 

 such winds as help to sweep the water a\\ay from the coasts. 



It is probable that the most important causes of the annual 

 fluctuations in the height of the water on the northern coasts may 

 be found in the different distribution of atmospheric pressure in 

 summer and winter and the winds which are dependent upon this. 



On pi. 21, I have given the down- fall curves for 1899 witli 

 crossed lines for the stations at Svolvær, Skomvær, Tromsø and 

 Alten, and have based them upon ..Nedbøriagttagelser'' (Ob- 

 servations on Downfall) published by the Norwegian Meteorolo- 

 gical Institute. Similarly, the normal curves for the same stations 

 are given in straiglit lines for a period of observation from 13 to 

 29 years. 



From these curves, it will be seen that, in a single yeai'. there 

 may be great divergence from the normal downfall. 



It is evident that the fluctuations in the amount of downfall 

 exei't an influence on the temperature and salinity of the sea. By 

 increasing the height of the Avater in the fiords, the downfall also 

 has some influence in producing currents. In the chaptei- dealing 

 with the cod fishery in Lofoten, I will try to prove that there is 

 a correspondence between the fishery results and the variations in 

 the distribution of atmospheric pressure, and will, in so doing, use 

 the height of the downfall as a measui'c of the influence of tlie 

 A\'inds. 



c. Biological Notes. 



The problem of tlic vertical distribution of living beings lias 

 occupied many biologists. I will not here treat of it at length, but 

 only mention a few facts. 



As far back as 1835, Michael Sahs*) divided our seaweed 

 belt into the following 4 zones: — (1) That of the Balanns, 

 (2) that of the Patelhi, (3) of the corals, and (4) that of the La- 

 mi naria. The greater depths had at that time been so little ex- 

 amined, that Sars could not attempt any division of the life found 

 there. Since 1835, however, this subject has occupied the atten- 

 tion of many, and several divisions have been made. But I will 

 only give here the one I prefer. Dr. Stuxberg has, in his book 

 „Evertebratfaunan i Sibiriens Ishaf", accepted the same division 

 for the animals as F. R. Kjell.mak^) for algae, viz: — 



(1) The littoral zone. 

 That part of the bottom, which is laid bare at low water, 

 and \\liicli in Norwegian is called „f.jærcn". 

 (2) The suUittond zone. 

 From low water' mai-k to the lower- limit for' algae. 



(3j The elittorul zone. 

 All that is below the lower- limit for' algae. 



1) Skandinavieus Stigninjj. Noi-ges Geor. Unders. Am-r). f. 1896^99. 



2) Kristiania 1902. 



•■') Die liydrogi-aphisciien Veiiiiiltnisse der oberen Wasserschicliten des iionl- 

 iidien Nurdineeres. Bilian^' t. K. Sven.ska Vet. Akad. Handliiigar B. 23, afd. II, 



■*) Beskriveiser og lagttagelser, p. VI. 



'') SuxBEKG refers to Kjellmax's treatise: — Ueber die Algenveiretation 

 des Murmansclien Meeres an der Westkiiste von Novaja Semlja und Waigatscli. 

 Nova Acta Heg. Soc. Scient. Ups., Ser. Ill, vol. e.\tra ordinem ediiinii. Upsala 

 1877. 



According to P. Buye,') the dividing line between the sublitto- 

 ral and elittoral zones is fixed by Kjellman at a depth of about 

 40 m. in Bohuslen, and this figure seems to suit the conditions on 

 the soutlnvest coast of Norway too. „0n the coasts of Nordland 

 and Firrmark", says M. Foslie in a letter to me, ,,algae may ge- 

 nerally be found down to 40—50 in., but vegetatioir mostly occur's 

 to a depth of only about 30 m." 



With regard to the vertical distribution of animals, STUXBERt; 

 fixes the limit between the sublittoral and elittoral zones in the 

 Sibei-ian polar water's at 30 — 40 fathoms, but I think it is best 

 to keep to the algologists' limit, for a lar'ge number of animals is 

 found irr the seaAveed zone. As far as I krrow, Norwegian alg- 

 ologists have accepted Kjellman's division, and I would suggest 

 that zoologists also should test its practicability for animals too. 

 If it be necessary to have a finer division, Michael Saks's zones 

 should be given a new ti'ial. 



As algae vegetation only r'eaches down to a certain depth, the 

 (|uairtity will to some extent depend upon the inclinatiorr of the bot- 

 tom. On a rock which forms an angle of 30" with the hoi'izon, 

 ther'c Avill, other things being equal, be much moi-e algae than if 

 the rock were per'pendiculai'. The space between the shor'e line 

 and the lower algae limit, which may be called the growing area 

 for algae, has a definitB propoi'tion to the angle of inclination. Here 

 again the same remar'ks as on page 230 ai-e applicable, and the 

 same mathematical explarrafion stands good. It will be found that 

 the growing ar-eas are in iiivorse propoi'tion to the sinus of the 

 andes of inclination. 



') Bidiag tir Knndskaben oni Algevegetationen ved Norgi^s Vestkyst 

 Berg. Mus. Aarb. 189.1—95. No. XVI. 



