106 
CAPTAIN F. W. BEECHEY ON THE TIDES IN 
Peculiar 
feature of the 
tides. 
Times of 
slack water 
tluroughout 
the channel. 
Course of the 
central por- 
tion of the 
stream in the 
south 
channel. 
she will be benefited by standing in shore or otherwise ; and will warn her of the 
danger of drawing near the shores of Cardigan or Caernarvon Bays, with particular 
tides and scant winds, and so likewise of the danger of standing close to the banks 
skirting the Irish coast in light winds. 
But it is not to the navigator alone that these observations will, I hope, be found 
useful : they will, I think, be interesting to men of science. Taken in connection 
with the very valuable series of observations which were carried round Ireland by 
the Ordnance at the suggestion of Professor Airy, we are made acquainted with 
several curious facts : first, that whilst it is high water at one end of the channel, it 
is low water at the other ; that the same stream makes both high and low water at 
the same time ; that there are two spots in the channel, in one of which the stream 
runs with considerable velocity without the water either rising or falling, and in the 
other, that the water rises and falls, from sixteen to twenty feet without having any 
visible horizontal motion of its surface ; and that during the first half of the flowing, 
and last half of the ebbing, tide-wave, the stream in the south channel runs in a 
contrary direction to the wave, and goes up an ascent of about one foot in 4^ miles. 
(See Plate IV.) 
To the lines of direction of the stream I have added the rate of the tide at its 
greatest velocity on the day of syzygy, and have reduced all to the same standard. 
I shall now proceed to describe the general course of the streams throughout 
the channel; point out the situations in which the meeting of the tides occurs; 
and offer such remarks on the course of the stream and upon the tidal pheno- 
mena of this sea, as will, I conceive, benefit the navigator, and be interesting to 
science. 
An inspection of the chart (Plate II.) will show that the tide enters the Irish Sea by 
two channels ; of which Carnsore Point and Pembroke are the limits of the southern 
one, and Rathlin and the Mull of Kintire the boundaries of the northern. 
The stream in the southern channel (as before stated) has been ascertained to 
move simultaneously in one vast current throughout ; running six hours nearly each 
way, at an average rate of from two to three knots per hour at the height of the 
springs, increasing to four knots and upwards near the banks and at the pitch of 
the headlands ; its times of slack water corresponding sufficiently near for all prac- 
tical purposes, with the times of high and low water for the day at Morecomhe Bay, or 
more correctly at Fleetwood, which is twelve minutes earlier than Liverpool. 
The central portion of the stream of flood or ingoing stream, runs nearly in a line 
from a point midway between the Tuskar and the Bishops, to one six miles due west 
of Holyhead ; beyond which it begins to expand eastward and westward, but its 
main body preserves its direction straight forward for the Calf of Man, which it 
passes to the eastward with increased velocity as far as Langness Point, and then at 
a more moderate rate on towards Maughold Head. Here it is arrested by the flood 
or southern stream from the north channel coming round the Point of Ayre, and 
