[w. BELL DAWSON] TIDES IN GULF AND UIVER ST. LAWRENCE 63 



111 Nortlminberliind strait, this altonuitioii appears to result from a 

 variation in the amount of the diurnal inequality itself, with the ]n\>- 

 gress of the tide. In the following comparisons, the amount given for 

 this diurnal inequality in the difference, is the highest value of the 

 average of two consecutive second differences. The amounts given for 

 the differences themselves, are as before the average of the three highest 

 and three lowest values, in order to avoid too great reliance upon indi- 

 vidual observations. The differences are all in absolute time. 



As the tide at Charlottetown is the latest intime and has also the 

 greatest range, comparisons were tirst made between that port and the 

 simultaneous observations at Halifax, St. Paul island, and Pictou ; and 

 with the tide tables for Quebec, calculated from the Quebec records. 

 The tide reaches Charlottetown and Quebec by channels and estuaries in 

 a somewhat similar way ; and it was therefore hojîed that the difference 

 in time might be fairly constant ; but it proved to be quite the contrary. 

 The observations at Charlottetown extended from June 20th to 26th ; 

 July 18th to September 7th ; and October Tth to N'ovember 25th ; 

 comprising in all 157 tides. The differences are as follows : — 



Charlotfetoivn aiid Quebec. (Charlottetown earlier.) 



Difference in the time of H. W. ranges from 6h. 06m. to lOli. .59m. 



Range in the dilîei'ence, 4h. 53m. Average clitierence=8h. 17m. 



Diurnal inequality in the difference =3h. 2.5m. 



Charlottetown and Halifax. (Charlottetown later.) 



Difference in the time of H. W. ranges from Ih. 01m. to .5h. 49m. 



Range in the difference, 4h. 48m. Average diffei'ence=3h. 02m. 



Diurnal inequality in the difterence=2h. 57m. 



Charlottetown and St. Paul island. Distance 2^30 miles. 



Dirterence in the time of H. W. ranges from Oh. 44m. to 4h. 05m. 



Range in the difference, 3h. 21m. Average difference = 2h. 21m. 



Diurnal inequality in the difference = lh. IGm. 



Charlottetown and Pictou. Distance .50 miles. 



Difference in time of H. W., from Oh. 19m. earlier, to 2h. 4.Sm. later. 



Range in the difference, 3h. 07m. Average difference = lh. 02m. 



Diurnal inequality in the difference = lh. 24m. 



although this inequality seldom exceeds Oh. 48m. 



The results for Pictou are less irregular. The observations there 

 extended continuously from June 4th to November 1st ; giving in all, 

 comparisons for 285 tides. The differences, obtained in the same wa}-, 

 are as follows : — 



Pictou and Halifax. (Pictou later than Halifax.) 

 Difference in the time of H. W. ranges from Oh. 14m. to 4h. 14m. 

 Range in the difference, 4h. OOm. Average difference=2h. 09m. 

 Diurnal inequality in the difference=3h. 12ni. 



Pictou and St. Paul island. Distance 180 miles. 

 Difference in the time of H. W. ranges from Oh. ;^m. to 2h. 46m. 

 Range in the difference, 2h. 12m. Average difference = lh. .3.5m. 

 Diurnal inequality in the difference=lh. 2(im. 



Sec. III., 1897. 4. 



