Tides and Tidal Currents in the Proximity of Land 



353 



completely general being independent of the actual dimensions of the basin 

 or of the period of the wave. It is consequently a simple matter to plot a series 

 of tidal data giving the elevations and time of H.W. in Greenwich time on 

 a similar semi-logarithmic co-ordinate system and by superposing the curves 

 on Fig. 144 to determine whether a satisfactory fit can be obtained. If this 

 is the case, the properties of the primary wave as determined by the position 



120° 1 00° SO" 60° 40° 20° 0° 340° G 



-20" -40° -60° -80° -100° -120° 



TIME OF HIGH WATER . <7I„ 



Fig. 146. Upper part: chart of Long Island Sound showing stations and co-phase lines. 

 Lower part: analysis of Long Island Sound system. 



of the points on the nomogram may be transferred to charts or diagrams 

 in which the geographical position of the points are indicated, and these 

 may be used to determine the distribution of phase differences of the primary 

 and reflected wave in the channel. 



In an entirely similar way the relations of equations (XI. 26 and 28) may 

 be combined to construct a graph in which the local time of H.W. at H is 

 related to that of slack water ot s , as in Fig. 145. This figure may be used 

 to check the adequacy of the theoretical treatment and to predict the ex- 

 pected time of slack water from data of the time of H.W. 



23 



