American Association. 2-53 



more extensively distributed than hitherto supposed : — " It was well 

 known that when the tide flowed into any bay whose mouth was favor- 

 ably placed for the reception of the tide wave flowing in, the height 

 of the tide increased as it advanced towards the head of the bay. 

 Extended observations went to show that the same phenomenon 

 was observable in the greater divisions of the coast. He divided 

 the Atlantic coast into three great parts, which he called the great 

 southern, great middle and great eastern bays. The first extended 

 from Cape Florida to Cape Hatteras, the second from Cape Hat- 

 teras to Cape Cod, the third thence to Cape Sable and perchance 

 to Cape Eace. His own observations extended as far north as 

 Cape Ann, and he had been assisted in making up the results by 

 Mr. Portalis. The tidal observations for Few Brunswick and 

 Nova Scotia (including Cape Breton), and part of Newfoundland, 

 were obtained from Captain Sliortland and Admiral Bayfield of 

 the Eoyal Navy, whom he desired thus publicly to thank for their 

 kindness. He should make no farther use of the information they 

 had communicated to him than as helping out the illustration of 

 his theory of the rest of the coast of North America, leaving them 

 to bring before the public and reap the honor of their own investi- 

 gations. Pursuing his subject, he showed that at the southern 

 headland of the southern bay. Cape Florida, the mean tide was 

 1-1 0th foot ; at Cape Hatteras, the northern headland 2 feet ; while 

 at Savannah, at the bottom of the bay, it rose to 6 feet, and 

 it was found that the tidal lines between these points correspond- 

 ed with the lines of the coast. At Cape Hatteras, again, and 

 Cape Cod on Nantucket, the tides were the same, (2), while at 

 New York, the bottom of this bay, they rose to 7. At Nantucket 

 the transition from the regime of the middle to the eastern bay was 

 sudden, and they had within a few miles five co-tidal lines touch- 

 ing the coast, which elsewhere were widely apart. From Cape 

 Cod to Cape Ann, at the bottom of the great eastern bay, there 

 was a rise of from 2 to 8 or 9, diminishing again at Cape Sable to 

 6, but he had reason to believe that this bay really extended to 

 Cape Race. He next proceeded to notice the several bays and 

 inlets along the coast, which generally showed the same charac- 

 teristics in a more marked manner. In the Bay of Fundy, for 

 instance, the height of the tides increased from Portland to Grand 

 Manan from 8 or 9 to lY, and thence to the bottom of the bay to 

 36. Prof. Bache's paper was illustrated with some very interest- 

 ing diagrams and charts, shewing the Avondeifnl coincidence of 



