538 TEE POPULAR SCIENCE MONTHLY 



sea : The English Channel ; the Irish Sea ; the Adriatic Sea ; the Gulf 

 of St. Lawrence ; the Gulf of Maine, including the Bay of Fundy ; Long 

 Island Sound; Bahia Grande; the Gulf of California; the Gulf of 

 Georgia; and Norton Sound. These waves are accompanied by pro- 

 gressive waves, setting inwardly; and the effects of the deflecting force 

 of the earth's rotation upon the moving waters are generally more or 

 less apparent. As a consequence, nodal lines, such as characterize 

 simple stationary waves, are more or less concealed in the bodies of 

 water just mentioned. 



Tides in the Vicinity of New York 



Turning now to the chart of cotidal lines for New York Harbor and 

 approaches (Fig. 8), several items may be noted: 



The tidal hour changes rapidly along the southeastern coast of Nan- 

 tucket Island. Here the range of tide is small. Over Cape Cod Bay 

 the time of tide is simultaneous, and the mean range exceeds nine feet. 

 Through Muskeget Channel the tidal hour changes rapidly and the 

 currents are hydraulic in character; i. e., the flood and ebb are not 

 oscillatory, but simply flow towards the body of water which is tempo- 

 rarily the lower. A similar remark is approximately true for Vineyard 

 Sound. Over Buzzards Bay the tide is nearly simultaneous, indicating 

 the stationary character of the tide wave. A similar remark is approxi- 

 mately true for Narragansett Bay. 



The proposed Cape Cod Ship Canal will connect the waters of Cape 

 Cod Bay at a locality where the average rise and fall of the tide is 

 nearly ten feet with those of Buzzards Bay, where the average range 

 scarcely exceeds four feet. The difference in level due to the tides will 

 suffice to produce in this canal, a tidal current having an ordinary max- 

 imum velocity of three knots per hour. 



In the eastern portion of Long Island Sound the time of tide 

 changes rapidly and the range of tide is small. Over the greater por- 

 tion of the Sound the tide is nearly simultaneous ; and the mean range 

 exceeds seven feet at the western end. The time and range of tide 

 change rapidly through East Kiver, and the tidal currents are hydraulic 

 and strong. West of the northern end of Blackwells Island, the ordi- 

 nary maximum velocity is five knots. Before the Hell Gate channel 

 was cleared of reefs and submerged rocks, the currents were a source of 

 much inconvenience and danger to all shipping passing through the 

 East Eiver. The time and range of tide change rapidly in Fire Island 

 Inlet, and the tidal currents are hydraulic and strong. A similar 

 remark is true for Barnegat Inlet. The tide in Earitan Bay consists 

 chiefly of a stationary wave. The tidal currents in Arthur Kill and 

 Kill van Kull are nearly hydraulic. The tide in the Hudson Eiver 

 consists chiefly of a progressive wave. 



