A TLANTIC COAST TIDES 503 



ward to nearly 11 feet in Cape Cod bay, and northward to about 

 15 feet at the entrance to the Bay of Fundy. On the coast of 

 Nova Scotia there is a similar increase northward from the 7-foot 

 tide of Cape Sable. Up the Bay of Fundy the increase in tidal 

 range' is rapid and parallel on the two shores — i. e., a line at 

 right angles to the axis of the bay connects points of equal 

 range. At the head of the bay the range is about 30 feet, and 

 thence it rapidly increases in the narrowing channels to 41 feet 

 at Monckton, on the Chignecto river, and 43J feet in the Basin 

 of Minas.* 



On examination of the times, it appears that high water 

 reaches the coast almost simultaneously from Cape Cod to the 

 head of the Bay of Fundy. Lines are sketched on the map 

 through places with the intervals ivh. 50 m. and vh. 10 m. to 

 illustrate this fact. These intervals are chosen because they are 

 means of a considerable number of stations and can therefore be 

 drawn with some confidence. Of particular value is the ivh. 

 50 m. line, closely determined on the Maine coast, on Grand 

 Manan, and at two stations in New Brunswick. Across the Bay 

 of Fundy, at its head, the island stations of Isle Haute, ivh. 

 49 m., and Black Rock, iv h. 58 m., fix the position of the line 

 equally well. That it cannot flex far to southwest before going 

 ashore is indicated by the spacing of the intervals along the 

 Nova Scotia coast. Annapolis must not be used for this pur- 

 pose, as it has a delayed bay-head tide. 



If the tide-wave advances on a line at right angles to its front, 

 we expect to find its front at right angles to the bay axis — that 

 is, northwest-southeast. ' It appears that the wave does not ad- 

 vance up the Bay of Fundy because, drawing the iv h. 50 m. line 

 with the utmost partiality to such a view, the greater part of its 

 length in the Bay of Fundy trends northeast-southwest. In 

 other words, the southern half of Nova Scotia seems to have al- 

 most no effect on the direction of the wave advance — or front, at 

 any rate — in the Bay of Fundy. Either the wave advances from 

 southeast to northwest, which is not .here supposable, or the 

 tide in the main bay is not a progressive wave at all. 



The cotidals are drawn on the assumption of a progressive 

 wave. The result is the reductio ad absurdam of that assumption. 

 The analysis of Mr Henry Mitchell t is in brief as follows : 



* These are mean ranges. 



f Physical Hydrography of the Coast of Maine, 1870. Ann. Rep. U. S. Coast Survey, 

 p. 175. 



