THE IRISH AND ENGLISH CHANNELS. 
115 
at a place called Coiirtown, a little above the contraction of the strait, and at 150 Comparison 
miles from Cape Clear (its entrance), there is scarcely any rise or fall of the water ; 
and in the other channel (about Swanage), situated also a little above the contraction 
of the strait, and just 150 miles from the Land’s End (the entrance of the channel), 
there is only five feet rise of the water at a spring range In both cases these 
points of small range of tide are situated on the opposite side of the channel to that 
of the high elevation above mentioned, and in both cases these spots are the node of 
the tide-wave (on either side of which the times of high and low water are reversed). 
And again we trace a similarity in an increased rise of the water on the south-east 
sides of both channels abreast of the virtual head of the tide : at Liverpool in one 
case, where the range amounts to thirty-two feet, and at Cayeux in the other, where 
it is thirty-four feet. 
It may also be shown that the progress of the tide-wave along the side of the chan- 
nels opposite the node is not very dissimilar. Reckoning in both cases from the line 
which we have before drawn as the outer limits of the channel, we find that in the 
English Channel from this line to Cherbourg, opposite the small range of tide, — 
Miles per hour. 
The wave travels 50 
In the Irish Channel, from a similar line to Bardsey, it travels 52 
From Cherbourg to Havre 32 
From Bardsey to Holyhead 16 
From Holyhead to end of tide 78 
Dieppe to the end of the tide 75^ 
and if 
complete 
would be 
in extent 
Miles. 
"616 
649 
397 
< 
193 
959 
..922 
These numbers are given roughly, merely for the purpose of showing the general re- 
semblance in the character and motion of the wave ; and it is probable a more 
judicious selection of positions and numbers would give a still nearer coincidence. 
Besides which we are somewhat uncertain as to the establishment at our starting- 
point. As a comparison, however, the numbers run fairly together. In both cases 
the retardation of the tide-wave about mid-channel, and the great elongation of the 
wave towards the end of the strait are remarkable, especially in the Irish Sea. 
Lastly, we may notice a singular coincidence in more respects than one, indeed, 
between the situation of the node placed by Professor Whewell'I' in the North Sea, 
and a corresponding point of small range and inversion of tide at the back of Kintire:|;. 
The node or hinge of the tide in the North Sea is curiously enough situated as nearly 
as possible at the same distance from the head of the tide off Dungeness, as the node 
at or near Swanage is on the opposite side of it ; and the node at Kintire communi- 
I in. "1 
: in. / 
5 ft. 1 in. mean. Philosophical Transactions, 1836, Part II. p. 320. 
* In 1834 it was 3 ft. 10 in. 
In 1835 it was 6 ft. 4 i 
t Philosophical Transactions, 1835, Part II. p. 298. 
t I have recently been apprised of this by Captain Robinson, R.N., who is surveying the coast of Scotland, 
but I have not seen the observations. 
Q 2 
