Section III, 1920 [55] Trans. R.S.C. 



The Analysis of Estuary Tidal Records by a Projection Method 



By Miss Violet Henry, M.Sc. 



Presented by Dr. A. S. Eve, F.R.S., F.R.S.C. 



(Read May Meeting, 1920) 



Summary 



An account of this method of analysis and of its application to 

 estuary tidal records was given by Dr. A. N. Shaw and the present 

 writer at the May meeting of The Royal Society of Canada in 1919, 

 and in an introduction incorporated with the paper. Dr. W. Bell 

 Dawson, Superintendent of Tidal Surveys, pointed out the importance 

 of investigations along these lines. As that paper ^ is available to all 

 those interested, and as a further and inclusive report of the whole 

 investigation will be prepared, it was considered by the writer that a 

 summary would suffice to call further attention to the development 

 of the method, and to put on record the reading of this report. 



In the case of estuary tidal analysis by the customary harmonic 

 methods the Fourier constants are numerous and arbitrary in char- 

 acter, and they neither correspond individually to separate physical 

 factors nor do they even lead to the expression of any satisfactory 

 empirical relationship between any one tide and any other on the 

 same estuary. The report dealt with the further testing of the pro- 

 jection method of analysis, in which the number of constants is 

 limited to two or three and by means of which the tidal records at 

 various points on an estuary may be correlated. 



A description was given of an improved apparatus, which con- 

 sisted of a carefully constructed set of three concentric frameworks 

 which allowed increased freedom in the setting of a graph for pro- 

 jection. 



Slides were shown and data were submitted which illustrated 

 several cases of the application of the method. Any tidal graph for 

 any one of the tidal stations on the St. Lawrence estuary could be 

 projected into any other which was further up the river. Similar 

 projections were possible also, in the case of each of the estuaries 

 examined, for example that of Port Essington into that of Port 

 Simpson, in British Columbia; and that of Carter's Beacon into that 

 of Root Creek, in Hudson's Bay. 



'Shaw, A. N., and Henry, V., Trans. Roy. Soc. Can., Vol. 13, p. 139, (1919). 



