112 
CAPTAIN F. W. BEECHEY ON THE TIDES IN 
Curves of 
tide-waves 
of various 
ranges. 
Importance 
of the obser- 
vations being 
extended. 
Attempt to 
trace the 
course of the 
stream, and 
connect the 
tides of the 
Irish Sea 
with those of 
the English 
Channel. 
Difficulty of 
so doing. 
Discrepan- 
cies recon- 
ciled by the 
application 
of an offing 
stream set- 
ting in oppo- 
sition nearly 
to that of 
the channel 
stream. 
In these sections it will be seen what an unusual depression there is of the water- 
line between Holyhead and Bardsey, and as this occurs at the time of slack water 
throughout the channel, we may perhaps connect with it the inversion of the interval 
of tide before mentioned at the former place. 
I conclude these remarks with directing your attention to another diagram, Plate V., 
exhibiting the curves assumed by the tide-wave in various parts of the Irish and 
Bristol Channels. They are given without any corrections having been applied to 
them. 
Having now laid before you the result of our observations upon the tides of the 
Irish Sea, I wish to call your attention to the great importance of these observations 
being extended. Independent of the vast advantage of having a correct knowledge 
of the set of the stream at the entrance of two channels through which the greater 
part of the trade of this great maritime nation is conducted, I think I shall be able 
to show that in another point of view also, considerable interest attaches to the 
subject. 
That you may meet the question at once, I lay before you the result of an attempt 
I have made with the aid of the data we already possess, and especially those of Capt. 
Martin White, R.N., to trace the course of the stream from Pembroke to the Land’s 
End ; to connect the tides of the Irish Sea with those of the Bristol and English 
Channels, and finally with those of the offing ; or, in other words, to reconcile and 
reduce to a system the anomalous and apparently contradictory observations of our 
naval surveyors in that portion of our coast, by combining them with the information 
which the recent attention to the tides has already furnished. 
The first part of this attempt presented but few difficulties as the streams were 
tolerably regular, but for the last our data, at first sight, seemed to bar all progress. 
At the mouth of the English Channel especially, opposition presented itself at every 
step ; the observations projected upon the chart exhibited a frieze of arrows pointing 
in all directions “in happy discordance,” and certainly quite useless and unintelli- 
gible to the navigator. Relying however upon the general accuracy of the observa- 
tions, I was encouraged to proceed. After some consideration it seemed evident 
that the water was influenced by forces acting in opposition nearly to each other, 
and that there was a tide in the offing whose streams of ebb and flood did not cor- 
respond with those of the channels. By applying this idea first to the English 
Channel, I found the observations responded to it ; and carrying it to the offing of 
the Irish Sea, and considering that channel as comprising the Bristol Channel within 
its limits, as the English Channel does the Gulf of St. Malo, I had the satisfaction of 
finding the correctness of the idea confirmed so far as the observations themselves 
extended. This offing stream appears to be of great extent, setting to the north and 
south along the coast of Biscay and the British Isles, running six hours nearly each 
way, and exercising an influence with more or less effect over all the waters of the 
channels and estuaries it passes in its progress, diverting their courses, and in some 
