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VI. Report of Observations made upon the Tides in the Irish Sea, and upon the great 
similarity of Tidal Phenomena of the Irish and English Channels, and the im- 
portance of extending the Experiments round the Land’s End and up the English 
Channel. Embodied in a letter to the Hydrographer. By Captain F. W. Beechey, 
R.N., F.R.S. Communicated by G. B. Airy, Esq., F.R.S. S^c., Astronomer Royal. 
Received March 22, — Read March 29, 1848. 
Sir, London, February 19th, 1848. 
It is with much pleasure I lay before you the result of observations which have been 
made upon the tides in the Irish Sea, during the execution of the survey which has 
been entrusted to my charge. 
Up to the period of these observations the set of the tides in the Irish Sea had 
been greatly misunderstood, owing to the association of the turn of the stream with 
the rise and fall of the water on the shore ; and it was generally understood that as 
Holyhead was three hours later in its tides than places at the entrance of the channel, 
a vessel starting with the first of the flood would earrynine hours’ tide in her favour 
in her run up ehannel and vice versd. 
This was an error sufficiently great in itself, but it was liable to be increased by 
an entire ignorance as to the time when a vessel would take any particular tide ; for 
the times of high water by the shore were very various on different sides of the 
channel. 
The present inquiry, I am happy to inform you, has set these errors and doubts at 
rest. The observations have shown that, notwithstanding the variety of times of 
high water throughout the channel, the turn of the stream is simultaneous ; that the 
northern and southern streams in both channels commence and end in all parts 
(practically speaking) at the same time, and that time happens to correspond with 
the time of high and low water on the shore at Morecombe Bay ; an estuary rendered 
remarkable as being the point where the opposite tides coming round the extremities 
of Ireland, finally meet. So that it is necessary only to know the times of high and 
low water at Moreeombe Bay to determine the hour when the stream of either tide 
will commence or terminate; a fact which will, I am sure, be fully appreciated by 
every person navigating the Irish Channel at night, or in thick weather. 
The chart of curves or lines of direction of the stream, Plate II., which accompa- 
nies this report, will show at once the effect of the tide upon a vessel wherever she 
may be plaeed in the ehannel, and especially direct her where, with a beating wind, 
MDCCCXLVIII. p 
The stream 
in the Irish 
Channel 
hitherto mis- 
understood. 
Turn of the 
stream 
simultaneous 
throughout 
north and 
south 
channels. 
Meeting of 
tides. 
