60 ROYAL SOCIETY OF CANADA 



shore of the Gulf, from Miramichi bay along the north coast of Prince 

 Edward Island, can be referred to St. Paul island, by giving the time of 

 the tide as earlier than at that station. Northumberland strait forms 

 the third region, in which the tides must be referred also, directly or 

 indirectly, to St. Paul island. 



The reason of this division will become clearer in examining the tidal 

 differences derived from the observations. In obtaining the results, a 

 large number of trial comparisons were made ; but only the more import- 

 ant of these will now be referred to. 



The tides in Chaleurs bay show a fairly constant difference in time 

 with Southwest Point, Anticosti ; which thus enables them to be included 

 with the Quebec system. The latest tides in that bay are at Carleton, 

 with the exception of Dalhousie and Campbellton in the Eestigouche 

 river, whei-e complications with river influence would be found. The 

 difference, based upon simultaneous observations from July 1st to October 

 25th, is as follows : — 



Carleton, Chaleurs Bay ; and Southwest Point, Anticosti. 



Difference in time of H. W. ranges from Oh. 55m. to 21i. 27m. 



Range in the difference, Ih. 32m. Average difference=lh. 30m. later. 

 The differences for intermediate places in the bay and around the 

 Gaspé peninsula, may be interpolated from their difference of Establish- 

 ment, as on the Lower St. Lawrence. 



The wide range in the difference in the time of high water which 

 ■occurs in the Gulf, may be illustrated from a comparison between Neguac, 

 in Miramichi bay, and Pictou. The difference between these stations 

 was found to range from 3'^ 04"' to 6'' 16'", showing a range of 3"^ 12'". 



On the shore of the open Gulf from Miramichi bay towards Cabot 

 strait, the time of high water must be taken as earlier than at St. Paul 

 island, for the reasons explained. As the tide at Neguac in Mii-amichi 

 bay, is the earliest in time of the tidal stations in this region, the value 

 for its difference with St. Paul island was first worked out ; and in doing 

 80 one of the features which here characterize the tide was taken advan- 

 tao'e of. In this region the Establishment is closely the same as the mean 

 luni-tidal interval throughout the course of the month. As the interval 

 thus varies little with the moon's age, a larger number of individual 

 tides become available in determining the P^stablishment, and irregular- 

 ities from other causes can be better eliminated ; and also differences of 

 Establishment are closely the same as direct differences in the time of 

 high water taken throughout the month. 



The Establishments at Neguac and St. Paul island were accordingly 

 determined from sets of four consecutive tides, namely the 2nd, 3rd, -Ith 

 and 5th, following full and change of the moon ; an even number of tides 

 being taken to eliminate the diurnal inequality in the luni-tidal interval. 

 At Neguac there were only four semi-lunations at which good observ- 



