SECT. 5] 



789 



I 0+3+6 +9h +3 +6 +9 +12 +I5h +3 +6 +9 +12 +I5h -9 -6 -3 +3 +6h 



9-6-3 +3 +6h 



9-6-3 +3 +6h 



9 -6 -3 +3 +6h 



Fig. 18. Tidal curves in rivers Ems, Hunte, Elbe and Eider. Full lines, observations at 

 tide gauges; broken lines, values as computed by difference method. 



