22 FISHING GKOUNDS OF NOETH AMERICA. 



" The meeting ami overlapping of tidal waves of different ages, that is to say, the tide of 

 to-day meeting the tide of twelve hours ago, and producing a double overlapping tide, is of rare 

 occurrence, and is due to the configuration of the sea bottom conjointly with the relative position 

 of islands and neighboring coast lines. 



"Northumberland Straits and the north shore of Prince Edward's Island afford the most 

 remarkable instances on the American continent of tlie meeting of tides of different ages, and it 

 can scarcely be doubted that the long and continuous line of inshore eddies, produced in a large 

 measure by this singular confluence, conjointly with the low temperature resulting from the 

 mixing of cold underlying with warm surface sea-strata, is the chief cause why mackerel fishing- 

 grounds should be there so close inshore with such undcviating constancy. 



"rt. The Prince Udicard's Island double tide. — The tidal wave, entering the Gulf of Saint 

 Lawrence between Cape Breton and Newfoundland, rushes with great rapidity along the edge 

 of the bank forming the boundary of the sixty-fathom line of soundings. It sends off lateral 

 waves toward the Straits of Belle Isle and toward Prince Edward's Island, while the main wave, 

 following the deep water at the edge of the sixty-fathom line of soundings, pursues a rapid 

 course toward aud up the Lawrence estuary, and reaches Caj e Chatte and Point de Monts 

 preciselj' at noon on the days of full and change of the moon. 



" Regarding for the present the lateral wave wliicli strikes off toward the southwestern 

 portion of the Gulf, we find it split into two portions by the Magdalen Islands; one-half, 

 namely, the eastern part, sweeps past the shores of Cape Breton and reaches the east peint of 

 Prince Edward's Island at eight hours thirty minutes, Cai)e Bear at nine hours, and the middle 

 of the straits ojiposite Hillsborough Bay at ten hours. Here it meets a flood tidal wave coming 

 down Northumberland Strait from the northwest, but this wave is not the other half of the 

 wave which was split by the Magdalen Islands two hours before; it is the tidal wave twelve 

 hours old, which has been delayed in its detour round the noi'th part of the Magdalens and 

 over the shallows of the Bradelle and Orphan Banks. A line drawn through the Magdalen 

 Islands, Eoche's Point, and the mouth of Hillsborough Eiver, in Prince Edward's Island, and 

 Wallace Harbor, in Nova Scotia, will pass through the places where the overlapping of the 

 confluent tidal waves takes place, at the full and change of the moon, near the shores of Prince 

 Edward's Island. ... 



"Admiral Bayfield is of opinion that these waves of ditterent ages, one being twelve hours 

 younger than the other, meet on the north side of the great bight of Prince Edward's Island, 

 between Traca,die Harbor and Savage Harbor. On the Admiralty charts this locality is desig- 

 nated by the words "Tides Meet." The current is inshore toward this point, both from North 

 Point and East Point, and the effect of the indraft is to determine toward the coast line the 

 floating or free-swinnning food of the herring and the mackerel. The great bight formed by 

 the concave northern coast line of Prince Edward's Island is the result of ages of action on the 

 part of these confluent tidal waves dragging along the sloping beaches, and washing away the 

 resulting debris from the sandstone rocks, of which a large part of this coast line is composed. 

 The ceaseless operation of these forces is thus manifested in the wearing away of the shores 

 most subject to their influences. 



"&. Tlie eddy flood tide in the estuary of the Saint Laiorence. — According to Admiral Bayfield, 

 the flood tide in the estuary of the Saint Lawrence, beginning at Auticosti and proceeding some 

 miles above Bic, rushes up the broad midchannel as far as Eed Islet and Green Island, where 

 part of it, being obstructed by the islands, turns round and, as an eddy flood tide, sweeps along 



