ATLANTIC ESTUARINE TIDES 



405 



and so far the ranges are still increasing. The larger rivers are 

 interrupted b}' rapids at the fall line before the ranges diminish, 

 usually close to the highest station observed. 



ST LAWRENCE TIDES 



The St Lawrence is an excellent example of a tidal estuary, 

 and it is to be desired that more and more reliable data may 

 some day be forthcoming for its study. For the present purpose 

 we must exclude the portion of the so-called river between Pointe 

 cles Monts and Anticosti, where the tides are unexplained. The 

 " bay " and river remaining are 283 miles long and 40 miles wide 

 at the mouth. When high water has reached Three Rivers a 

 second high water appears at the east end of Anticosti. The bay 

 includes the waters between Pointe des Monts and Isle Royale, 

 whence it is river to Three Rivers. The U. S. Tide Tables give 

 22 stations here, from which a table has been prepared as before. 



St Lawrence Tides 







I 



II 



III 



IV 



V 



VI 



VII 



VIII 



IX 



H.W. interval from Pointe 

 des Monts. 







125 



30 



26 



21 



23 



14 



17 



13 



14 



H. W. advance in last hour 

 (miles). 



9.2 



12.9 



13.3 



14.4 



13.9 



13.3 



11.0 



8 



3 



2 



Mean tide range (feet). 



h. TO. 



h. m. 



h. to. 



h. m. 



h. to. 



h. TO. 



h. m. 



h. m. 



h. m. 



h. to. 





6 20 



5 55 



5 47 



5 33 



5 30 



5 11 



5 10 



5 10 



5 7 



5 5 



Duration of rise. 



6 5 



6 30 



6 38 



G 52 



6 55 



7 14 



7 15 



7 15 



7 18 



7 20 



Duration of fall. 



During the first four hours the tide travels up the bay with 

 lessening speed, while the tide, range steadily augments ; then 

 the advance is irregular an'd the range diminishes. At Three 

 Rivers, the head of observations, the rise of tide lasts 5 h. ; the 

 fall, 7 h. 25 m.— not a strong steepening of the wave front after 

 283 miles of travel. This may be due to the great depth of the 

 St Lawrence. The Penobscot is in these respects comparable- 



The Bay of Chaleurs, a hundred miles long and twenty miles 

 wide at the mouth, affords a good bay, the ranges mounting up 

 from 4 feet to 7.6 feet and high water being delayed. There are 

 but nine stations in the tide tables, which rather hint at the facts 

 than elucidate them. It is clear that the tide-wave advances 

 with its front looped deeply into the bay, as is probable with the 

 St Lawrence and all deep bays. 



