472 WHA T IS THE TIDE OF THE OPEN ATLANTIC? 



The duration of rise is greater than that of fall, and grows still 

 more so up the bay. 



Westport, bay mouth : rise 6h. 31m.. fall 5b. 54m. 



Wareham R., bay head : rise 6h. 55m., fall 5h. 30m. 



This is anomalous, yet it is to be remembered that there is no 

 progression between these. points — the tide reaches them about 

 the same time. 



Narragansett bay is an undoubted drowned river, or rather 

 two of them. The several channels complicate the topography. 

 The ranges mount up from 3.1 feet and 3.6 feet at the entrance 

 to 4.9 feet at Nayat point. Thence it diminishes to 4.4 feet at 

 Providence. Even here the close adjustment of cotidals to shore 

 contours appears in the fact of nearly simultaneous high water 

 at Sakonnet, Prudence light, and Point Judith. The lingering 

 rise of the tide noted in Buzzards bay appears here also. 



Bay mouth : rise 6h. 25m., fall 6h. 



Bay head : rise 7h. 5m., fall 5h. 10m. 



The bay-head observation is at Providence, where there is 

 some tidal progression. In this case, then, the wave has be- 

 come less steep-fronted as it advances. 



In Vineyard sound again the cotidals are seen to be contour- 

 ing ones and strongly contouring. It is difficult to comprehend 

 how this can be a local development of a long wave front pro- 

 gressing across the Atlantic. Only from Ga} T Head to Woods 

 Holl are there clear signs of progression. 



In the Bay of Fundy high water reaches points near the head 

 of the main bay a few minutes before reaching the Maine coast, 

 just outside the bay entrance. Long Island sound gives another 

 surprising illustration of the same tendency. This conception 

 of a contouring wave front seems to introduce an element of con- 

 fusion. There is something very reasonable, simple, and satis- 

 factory in the earlier idea of a long wave-crest, straight or only 

 gently curving on a long radius ; yet even in the shallow waters 

 that rear up considerable waves this view is seen to be untenable. 

 Thus the tide reaches Sandy Hook 30 to 45 minutes earlier than 

 points farther out to east and south ; so also in St Peters bay, 

 Cape Breton island. As already stated, this contouring tendenc} 7, 

 of the cotidals became evident to Dr Whewell as soon as he had 

 good data to work on. He saw that on the Atlantic coast of 

 North America, too, the lines must be bent along shore, though 

 he did not draw them. 



Airy, in the Encyclopaedia Metropolitan a, suggests that the 



