746 



pour their waters into these gulfs, and in both raise the tide to the 

 extraordinary elevation of forty-seven feet. From the Land's End 

 to the meeting of these streams in one case is seventy-five miles, and 

 in the other the same. 



In one channel, at Courtown, a little way above the contraction, 

 and at 150 miles from the entrance, there is little or no rise of the 

 water; and in the other, about Swana2:e, at the same distance from 

 the entrance, there is but a small rise of tide also (five feet at springs). 

 In both cases these spots are the node or hinge of the tide-wave, on 

 either side of which the times of high water are reversed. And 

 again, near the virtual head of the tide, in both cases there is an in- 

 creased elevation of the water on the south-east side of the channel 

 of about one-third of the column ; the rise at Liverpool being thirty- 

 one feet, and at Cayeux thirty-four feet 



The author traces a further identity in the progress of the tide- 

 wave along the sides of both channels opposite to that of the node. 

 In the first part of the channel the wave in each travels at about 

 fift}'' miles per hour; in the next, just above the node, this rate is 

 brought down to about thirty miles per hour in one, and to sixteen 

 miles in the other; it then in both becomes accelerated, and attains 

 to about seventy-six miles per hour. 



Lastly, the author observes that the node or hinge of the tide, 

 placed b)'' Professor Whewell (in his papers on the Tides) in the 

 North Sea, is situated at the same distance nearly from the head of 

 the tide off Dungeness, as the node near Swanage is on the opposite 

 side of it ; and that in the Irish Channel, at the same distance nearly 

 as the node at Courtown is from the head of the tide off Peel, there 

 is a similar spot of no rise recently observed by Captain Robinson. 



The author concludes this paper by urging a further investigation 

 of the tidal phenomena of the English Channel, on the ground of the 

 great advantage navigation, as well as science in general, would de- 

 rive from such an examination. 



Captain Beechey's letter is illustrated by twelve charts and dia- 

 grams, showing the identity and singular phenomena of these two 

 great channels. 



March 23, 1848. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



" Observations on some Belemnites and other fossil remains of 

 Cephalopoda, discovered by Mr. Reginald Neville Mantell, C.E., in 

 the Oxford Clay, near Trowbridge in Wiltshire." By Gideon Algernon 

 Mantell, Esq., LL.D., F.R.S., Vice-President of the Geological 

 Societ5^ 



The author states, that a line of railway now in progress of con- 

 struction to connect the large manufacturing town of Trowbridge 

 %vitli the Great Western, being part of the Wilts, Somerset, and 



