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Part HI. — Fifteenth Annual Report 



resultants at the English stations show a still greater increase in the 

 northerly element ; at the two Continental stations it is less marked and 

 resembles the condition at the Bell Kock. 



It seems, therefore, to be tolerably certain that during the time the 

 experiments were in progress the prevailing wind in the southern part of 

 the North Sea was somewhere about north-west, a direction which would, 

 in this case, rather favour the south-eastward movement of the water 

 from the Yorkshire coast towards the coast of Holland, where, however, 

 very few drifters were obtained. At Helder, the prevailing wind for the 

 last four months of 1894 was W. J N. (42*5), for 1895 it was also 

 W. | N. (105), and for 1896 W.N.W. \ W. (97), more westerly and 

 stronger than on the English coast (see figs. 6,13, 20, pi. xi.). Winds blow- 

 ing in this direction off the north coast of Holland would tend to drive the 

 surface water towards the coast of Schleswig, where very few drifters 

 were found. At the Scaw the resultant is only well marked in 1896, 

 and indicates a W.S.W. ^ W. wind, with a force or duration of 48. In 

 1895, it was N. (7-5), and for the four months of 1894 S.W. (9). If 

 south-west winds prevailed along the west coast of Deumark, as appears 

 likely, they would tend to move the surface water approximately in the 

 direction the drifters took at this part of the North Sea. 



From the above discussion of the effective winds during the period the 

 experiments were being made, it is, I think, evident that the direction of 

 the wind was approximately coincident with the general direction of the 

 movement of the surface water only at a limited portion of the southern 

 part of the east coast of England, on the west coast of Norway, and, 

 probably, at the northern part of the coast of Denmark. But the most 

 constant and outstanding feature in the experiments, the movement of 

 the water down the whole east coast of Scotland and the northern part of 

 the east coast of England, in a S. by W., S. and S. by E. direction, is a 

 movement at right angles to the prevailing winds, and cannot, therefore, 

 be due to their direct action. In the northern part of the east coast of 

 Scotland, the movement of the water is rather opposed to the prevailing 

 winds. 



The Tidal Streams. 



Before going further I may allude to another factor that may bear 

 upon this southerly movement of the water on our east coast, namely, the 

 tidal stream, which appeared to me at one time to be the most important. 

 The tidal wave which causes high water on the east coast travels in the 

 same direction as the movement of the surface water as shown by the 

 drifters ; southwards from Shetland in the north to Flamborough Head, 

 Yorkshire, in the south, at the rate of about 55 miles an hour ; and it 

 then passes to the east and northwards along the coasts of Holland and 

 Germany and Denmark. From the similarity of the direction taken by 

 the drifters, I assumed that the south-going tidal stream was probably the 

 efficient cause of their movement; but I have seen reason to modify this 

 view. In the first place, a high authority on the subject of the tides 

 around our coasts, to whom I wrote, assured me that the north-going ebb- 

 stream, which moves in the opposite direction, is stronger than the flood- 

 tide ; and that he would expect the majority of the drifters to be found 

 to the north of the place where they were thrown into the sea. From 

 the gradual rise of the bottom of the North Sea from north to south, one 

 would expect this to be the case, the inclination (as well as the prevailing 

 wind off the Scottish east coast) favouring a more rapid run to the north. 

 I endeavoured to learn the opinions of the coastguard at some parts 



