KEMAEKS ON THE TIDE TABLE. 285 



(2.) English Channel. — The Tides of the English Channel were but im- 

 perfectly understood till Eear-Admiral Beechey, K.N., investigated a mass 

 of observations which had been made about the year 1847, and which 

 demonstrated that there was a great resemblance in the characteristics of 

 the tidal phenomena of the English and Irish Channels, and this investi- 

 gation led to a more extensive series of observations throughout the 

 English Channel, which were also discussed by Admiral Beechey. From 

 his valuable contribution to science and the mariner, in the "Philosophical 

 Transactions" for 1848 and 1851, we make the following extract : — 



Instead of the progressive changes of stream turning progressively later 

 as the Tide advances up the strait, they cease at a certain point, which is, 

 in the English Channel, between the Start and Gulf of St. Malo ; and in 

 the North Sea, between the Texel and the Estuary of Lynn. Between 

 these spots there is a Tide peculiar to the Channel, quite distinct from 

 that of the seas on either side of it, which are always running in contrary 

 directions. 



When these streams meet, the Tide is ever varying in its direction, 

 according as the strength of one stream prevails over that of the other, 

 giving to the water a rotary motion, with scarcely an interval of slack 

 water; in the space between them the Tide sets steadily towards Dover, 

 while the water is rising there, and away from it while it is falling at that 

 place. This " true Channel Stream " is about 180 miles in extent in either 

 direction, from the point of union of the Tides in the Strait of Dover to 

 the region of rotatory Tides off Lynn, and off the Start and St. Malo. 



As the true Channel Streams are always running in opposite courses, 

 there is necessarily a point where they meet and separate, and this occurs 

 in the Strait of Dover. But in this strait, the stream, although it first 

 obeys one tide and then another, does not slack with the Channel Streams, 

 but is found to be still running at high and low water on the shore, at 

 which times those streams are at rest, so that the Strait of Dover never 

 has slack water throughout its whole extent at any time. I have, in con- 

 quence, called this an intermediate tide. 



The limits of neither of the streams appear to be stationary, but range 

 to and fro as the tide rises and falls at Dover, travelling to the Eastward 

 on both sides, and at high and low water suddenly shifting 60 miles to the 

 Westward to recommence their Easterly course with the next tide ; and, 

 although so far apart, they possess the remarkable peculiarity of shifting 

 together ; so that the Channel Streams preserve, as nearly as possible, the 

 same relative dimensions. 



In the Strait of Dover, this line of meeting and of separation oscillates 

 between Beachy Head and the North Foreland, a distance of about 60 

 miles. When the water on the shore at Dover begins to fall, a separation 

 of the Channel Streams begins off Beachy Head. As the fall continues, 

 this line creeps to the Eastward ; at two hours after high water it has 

 reached Hastings ; at three hours, Eye ; and thus it travels on, until at 

 low water by the shore it has arrived nearly at the North Foreland on one 

 side of the strait, and at Dunkirk on the other. At this time the Channel 

 Streams on both sides slack, but in that portion which I call the inter- 

 mediate stream, in the Strait of Dover, the water is still running to the 



