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the Atlantic arrives at the shores of the United Kingdom, a small portion of it 
passes eastward up the English Channel, through the straits of Dover, and then 
northward to the German Ocean ; another part flows northward up St. George's 
Channel, while the principal body of water continues its course to the westward 
of Ireland, and passes onwards much beyond our most northern limits. The two 
detached portions of this large body of water having to force their way through 
the narrow channels bef ore named, are consequently retarded in their progress, 
but the main tidal wave which traverses the more open sea with a higher velocity 
yet having a greater distance to travel, does not arrive at its northern limit till 
after the time the detached portions have made high water on the shores of the 
channels they traverse, so that the great tidal wave when it begins to ebb south- 
wardes forces large bodies of its waters between Scotland and Norway, and also 
down the North Channel which separates Ireland from Great Britain. The 
immense marine current sweeps along our eastern coasts and transports the material 
it has despoiled from the shores met with in its progress, and where there is not a 
sufficiently large and rapidly flowing stream of river water to an open channel, a 
bank is thrown across its mouth, and the river is either dammed back to form a 
lake, or the outlet deflected further south, as may be seen in the Murragh of 
Wicklow. Here we can trace the first process in the Broad Loch, as represented 
on the plan, and also the subsequent movements and accumulation of material to 
dam-in the Murragh Loch, and so on till the communication of the river Vartray 
with the Irish Channel has been diverted nearly three miles from its original 
position. No doubt at one period the river discharged itself directly into the sea, 
but as the Murragh of Wicftlow became gradually enlarged, the stream began to 
flow into the narrow lake, now known as the Murragh Loch, which ha3 been 
formed at its mouth by the bank thrown up by the sea across its original course.* 
The western shore of the Murragh Loch indicates the former line of sea coast. 
This great bank, known by the name of the Murragh of Wicklow, has now be- 
come so firmly consolidated that horse races annually take place on it. The race 
course is marked on the plan. The materials of which it is composed are various, 
pebbles, gravel, and sand, and much of the matter composing the bank must have 
been transported from considerable distances. Many fine pebbles are found on 
this bank, some of which, both polished, and in their rough state, are on the 
table, and also a measured plan. 
Sometimes the natives try to play tricks upon travellers by offering them common 
worthless pebbles for sale, and which they rub over with oil to give them a shining 
appearance, and also to bring out any colour they may possess* 
The observations made relative to the movements of the great tidal wave which 
approaches our shore twice in the day of twenty-four hours, will tend to explain 
the double tides, which are by no means unfrequent on the eastern coast of Ire- 
land. The explanation of this phenomenon is as follows : — When the main 
portion of the great tidal wave that passes to the westward and on to the north 
of Ireland, has turned its course southward, and its retrograde movement is 
accelerated by a strong north west gale, a large body of water is forced into the 
* Works are now in progress to convey the water from the river Vartray to Dublin. 
