146 



THE ROYAL SOCIETY OF CANADA 



Figure 2 



the tide is known at any one spot on an estuary it is suggested that a 

 practical development of this analysis would lead to the prediction of 

 the tidal record at any other place on the same estuary, when at 

 least one comparison of previous tides with those at the reference 

 station were available. A further reference may be possible to a set 

 of basic sinusoids, but this idea is not quite so promising. 



In Fig. 3 the agreement is not very good. We have attempted to 

 express one of the extreme forms of estuary tidal curves as a projec- 

 tion of pure sines. The broken line represents the tidal graph for 

 Levis, on June 23rd, 1917, and the continuous line from a to b repre- 

 sents the projection of a sine curve with A = 3 cm. and r= -54 at the 



Figure 3 



