Ixvi 



Thirty-third Annual Report 



them submerged at the surface, were thrown into the sea from the 

 " Goldseeker at various places, both near the coast and at a distance 

 from it, each bottle containing a numbered card for identification 

 later. Of a total of 5928 drift-bottles of this kind which have been 

 put into the sea to the end of the year 1914, 1070, or 18 per cent., 

 have been returned, partly from the British coast, but mostly from the 

 continental coasts, more especially from Denmark and Norway, and 

 some of them have been found as far north as the Lofoten Isles and the 

 North Cape, and a few even on the Murman Coast in Barents Sea. 

 The number of surface drift-bottles put into the sea last year was 

 832, and the number returned in the twelve months was 127, of which 

 3 had been set adrift in 1912, 32 in 1913, and the remainder in 1914. 

 A Report on the results of these experiments is in course of prepara- 

 tion. 



Similar investigations have been made to ascertain the movement 

 of the water at the bottom of the North Sea, by means of special 

 bottles, so w^eighted as to be carried along with the bottom cmTents. 

 The second Report, by Captain C. H. Brown, giving the results of these 

 investigations was published last year.* They confirm generally the 

 results of the previous investigation described by Captain Brown in 

 his first Report.! The bottom water appears to flow into the North 

 Sea through the Orkney- Shetland channel, the main stream flowing 

 to the southward into the Moray Firth and along the East Coast of 

 Scotland, an indraught into the Firth of Forth being well marked. 

 In the vicinity of the Long Forties, a branch from this southerly flow 

 trends to the eastward, and while this east-going stream apparently 

 sweeps right across to the Skagerak, the main stream bends sharply 

 to the northward, and fiov/s with increased velocity along the Norwegian 

 coast. The second series of observations, however, show that the 

 cyclonic system of deep currents, which, by the first investigations, 

 resolved itself into a more or less circular shape with a small central 

 axis situated somew^hat to the south of the Bressay Shoal, appears to 

 be considerably elongated, the major axis, or lane, of apparently still 

 water, extending along the meridian of Greenwich for about 60 miles. 

 To the w^estward of the Prime Meridian the flow is to the southward, 

 and in the east longitude there is a relatively rapid flow to the north- 

 ward, these two opposite streams being separated by only some 30 

 miles. 



The Mean Level of the Sea. 



A paper ; by Professor D'Arcy W. Thompson has been published 

 dealing with the subject of Mean Sea Level, and the fluctuations to 

 which this mean level is subject. Though mean sea level is, or is 

 .supposed to be, the datum to which all levels are referred in our 

 Ordnance Survey, it is a cmious fact that mean sea level has itself 

 never been accurately determined. Moreover, it is shown in the 

 present paper that the mean level of the sea is subject to fluctuations 

 .so numerous and so varied that in all probability it never can be 

 determined with accuracy, and all we can do is to approximate, during 

 a long course of years, nearer and nearer to a true determination. 



Fisheries, Scotland, Scientific Invest., 1913, ii. (August ]914). 

 t Fourth Report {N(rthern Area), North Sea I vestigations, 1009. 

 t Fisheries, Scotland, Scientific Invest., 1914, iv. (March 1915). 



