National Geographic : 1898 Dec
ATLANTIC COAST TIDES 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 43k 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 Iv h. 50 m. and v h. 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 iv h. 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, iv h. 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 absurdum of that assumption. The analysis of Mr Henry Mitchellt is in brief as follows: * These are mean ranges. t Physical Hydrography of the Coast of Maine, 1879. Ann. Rep. U. S . Coast Survey, p. 175.