On Mean, Sea Level and its Fluctuations. 



15 



Sa. 



Ssa. 



H. 



k. 



H. 



k. 



It is difficult, so far as I can see, to draw positive conclusions from 

 an inspection of these data. We observe in the case of the Norwegian 

 Stations, where the values are recorded for different epochs, that the 

 several determinations are often very discrepant ; but we may assume, 

 meanwhile, that this is, in part at least, the natural consequence 

 of those variations of still longer period which we shall afterwards 

 discuss. When we set down the various constants on the chart, and 

 attempt to correlate them according to their geographical position, 

 we meet with little success : the contom'-lines which come out 

 clearly and easily when we are dealing, for instance, with sea-tempera- 

 tm'es, evade us here. But, nevertheless, we seem able to detect some 

 appearance of regularity. The half-amplitude of the annual wave is 

 largest, so far as oiu- data go, at Dover ("GIS ft.) ; it is large (•45 ft. or 

 thereby) at Leith, Oban, Stromness, and at the northern Norwegian 

 stations. It appears to increase (1) as we go northward along the 

 West Coast of Great Britain from the Bristol Channel to Oban ; (2) 

 as we come southward along the East Coast of Scotland from Aberdeen 

 to Leith ; and (3) as we proceed northward along the Coast of Norway. 

 As we pass from the North Sea round Denmark to the Baltic, it appears 

 to grow smaller : its mean value for four stations from Bremerhaven 

 to Frederikshaven, near the Skaw, is "28 ft. ; at seven stations in the 

 Belts and Cattegat, -21 ft. ; and at three Baltic stations, from Trave- 

 munde to Memel, "20 ft. The median value for all om' recorded data 

 is '32 ft., with half the observed value between '25 and "42 ft. ; or 

 excluding the Norwegian records, "28 ft., with half the observed 

 value between '20 and '34 ft. 



The half-amplitude of the semi-annual 

 about one-third that of the annual wave, 

 or excludinfi the Norwegian stations, "09 ft. 



wave is, on the average, 



Its median value is '12 ft., 



and one-half the observed 



values lie between '07 and '12 ft. The Norwegian observations are 



