XIV ROYAL SOCIETY OF CANADA 



records obtained throughout tlie year 1895 at Quebec, Father Point and 

 Southwest Point. Anticosti, furnish an excellent basis of comparison. 

 Although the tide increases from a range of about 5 feet at Antieosti to 

 19 feet at Quebec, the tidal ditierences throughout the course of the lunar 

 month are remarkably constant. With two well established differences 

 for Father Point and Antieosti, it is, therefore, justifiable to base the 

 differences for intermediate places upon the difference of establishment 

 as given in the Admiralty list ; for, although these are obtained at full 

 and change of the moon and the luni-tidal interval itself varies through 

 a wide range during the month, yet the new observations show that 

 their differences will be practicall}^ constant throughout the course of the 

 month. The tidal differences for the St. Lawrence Eiver above Quebec 

 are derived from simultaneous observations at seven points during two 

 complete months in 1887 and 1888, taken by Mr. E. Steckel of the 

 Department of Public Works. The months chosen were during the 

 seasons of high and low level of the St. Lawrence Eiver, and the differ- 

 ences show that the tide wave is retarded by a few minutes during the 

 high level period as com))ared with the low level. The mean of these 

 ditierences is adopted, and also checked by comparison with the difference 

 from Quebec as given by a reduction of the observations of the semaphore 

 operator at Lotbinière throughout one season. 



The Quebec tide tables accompanied b}^ these tidal differences will 

 afford reliable information for the tidal portion of the St. Lawrence 

 waterway, which extends for 470- miles. In the tide tables for 1896, 

 ])u1)lislK'd by the Ignited States Coast and (xeodetic Survey, the tides in 

 this region from Cape Chatte to Three Elvers are referred successively 

 to Eangoon, India ; Sandy Hook, N.J., and St. John's, Newfoundland ; 

 and no tables for Quebec are given, which is the natural port of 

 re fe l'en ce. 



The comparative constiincy of the tidal differences in the Lower St. 

 Lawrence, is all the more remarkable, as at both the entrances by which 

 the (Juif of St. Lawrence communicates with the ocean, the tides are veiy 

 irregular, especiall}' in having an excessive diurnal inequality. These 

 entrances are commanded Ijy tide gauges at St. Paul Island, C. B., and 

 the Strait of Belle Isle ; but it has not 3'et been possible to obtain any 

 satisfactory differences between these stations and Sandy Hook or 

 Halifax. The difference between St. Paul Island and Antieosti, or tlie time 

 which the tide wave occupies in crossing the gull', is also very irregular, 

 as it varies from 4h. 30m. to 6h. 30m., without including exce])ti()nally 

 high and low values. The reason that these irregularities arc not carried 

 on into the Lower St. Lawrence does not appear, unless they may j^rove 

 to be due to some form of tidal interference which affects the gulf 

 entrances themselves, and disappears at the mouth of the St. Lawrence. 

 Someof these irregularities are observed, however, at Pictou and Charlotte- 



