THE TIDES 123 



Greater Maxima — 



1. A crest of 37 feet from trough to summit in the St. 

 Malo Bight. 



2. A crest of 42 feet from trough to summit at Portishead. 



3. A crest of 22 to 23 feet from trough to summit in the 

 Wash. 



Lesser Maxima — 



1. A crest of 24 to 28 feet in the EngHsh Channel between 

 Hastings and the Somme. 



2. A crest of 27 to 28 feet in Liverpool, Morecambe Bay, 

 and Solway Firth. 



3. A crest of 12 feet at the entrance to the River Weser. 



The three greater maxima occur almost simultaneously 

 between 6.30 and 7.30 G.M.T., and the lesser maxima between 

 10.45 ^nd 11.45 G.M.T. on full and change days. 



The undulation causing high-water in the EngHsh Channel 

 is from 15 to 16 feet in height on theEnglish coastfrom Land's 

 End to the Start, and from 19 to 23 feet on the French coast 

 from Ushant to Ile de Bas. It assumes a convex form as it 

 moves up the Channel, moving -more rapidly in the fairway 

 than along the coasts. 



On the French coast it is obstructed by the peninsula 

 terminating in Cape La Hague, the water backing up and 

 causing the tidal wave to reach a height of 37 feet at St. Malo. 



On the English coast, after passing the Start, its height 

 diminishes ownng to the latéral movement into Lyme Bay, so 

 that the height is only 9 feet at Portland and 7J at the Needles, 

 while at Cherbourg the undulation is about 18 feet high. 



By this time the undulation has been transformed into a 

 purely horizontal movement, the eastern part of the English 

 Channel being a large basin with a comparatively narrow 

 entrance between the Isle of Wight and Cape Barfleur. The 

 tide fills this basin at a great rate. After passing the Isle of 

 Wight and Cape La Hogue, the undulation increases con- 

 siderably in height, caused by the stream meeting that coming 



