46 THE ROYAL SOCIETY OF CANADA 



reference stations, but this is not easy when the tides themselves are 

 of so many different types. This tidal work was extended to British 

 Columbia in 1901. The results obtained will be found in the Tide 

 Tables for Eastern Canada and the Pacific coast, which are published 

 annually. 



Tide Levels. — From the inception of the work, it was made a prac- 

 tice to establish local bench-marks at all the tidal stations, whether 

 permanent or temporary. These have been of much service in the 

 individual harbours, for tide levels. At the principal tidal stations, 

 special trouble was also taken to maintain truly accurate levels; 

 and as a result, very reliable determinations of Mean Sea level have 

 been obtained. At the time, there were no levelling operations in 

 progress for which these determinations could be utilized. This 

 use of Mean Sea level was pointed out as early as 1903, and the fore- 

 sight of this Survey in the matter, is now bearing fruit; as three 

 departments in the Government service are now running extended 

 levels, and a Dictionary of Altitudes in Canada has been published 

 by a Government commission. For all such work, it is evident that 

 Mean Sea level is necessary as a basis; and the determinations made 

 by this Survey during a series of years, have furnished this basis' 

 ready-to-hand when levelling operations were undertaken. Two 

 special publications on tide levels have also been issued by the Super- 

 intendent for the benefit of Engineers, as these levels are also of value 

 in city works, in harbours, and for dredging purposes. 



Publications. Currents. — Information on the currents on the 

 Eastern coasts of Canada, are given in the following reports: — 



"The currents in the Gulf of St. Lawrence," including Belle Isle 

 and Cabot straits, and Northumberland strait. With map. 



"The currents in the entrance to the St. Lawrence," including 

 the Anticosti region and the Gaspé region. With map. 



"The currents in Belle Isle strait." With a chart and three plates. 



"The currents on the South-eastern coasts of Newfoundland." 

 With a chart and eight plates showing the set of the currents. 



"Tables of the currents in the Bay of Fundy." Giving the 

 direction and velocity of the tidal streams, hour by hour. With a 

 chart of the currents. 



Tides. — Tide tables are published annually as follow: — "Tide 

 Tables for Eastern Canada," including the principal harbours and 

 reference stations, with information on the tidal streams in the Tra- 

 verse, and in the straits in the Gulf region. "Tide Tables for the 

 Pacific coast," with tables of slack water in the leading passes and 

 narrows, to which twelve other passes are referred by difference of 

 time. Three abridged editions of these tide tables are issued, which 



