74 PAPERS ON TRANSATLANTIC COMMUNICATION
Horril Rocks.
Ballast.
The Hole.
Cock Rock.
Coonagh Point.
Pool.
Tides.
Tides.
General Remarks.
and 10 feet water close outside of it.
About four cables' lengths higher up there is another cluster of rocks, the breast-mark of which is the two castles of Cratloe in one ; above this are the Horril Rocks, which extend beyond the line of mud, and uncover every spring tide, and lastly a collection of stones, called the Ballast.
Here the channel takes a turn to the S.S.W.,
leading an extensive mud-bank stretching from Muckinish Point to the S.E.
half a mile, and leaving a channel between it and the opposite shore of only 150 yards, which breadth continues up to Limerick.
In this reach, which is called the Hole, just above the Ballast, there is deeper water than usual, from 12 to 15 feet, for about three or four cables' lengths, and vessels finding they cannot reach Limerick with die tide would do well to anchor here.
The next difficulty is the Cock Rock, formed of large masses of rock lying on a gravel bed, running off from the western shore under Teervo House to .yards
Coonagh House, and narrowing the channel to only 40 yards.
There is a sharp leading-mark for this passage, which is the little castle of Cratloe, or Cratloekyle, in one with a remarkable white farm-house, half way up the Cratloe Hills, bearing north.
Just above the Cock Rock, in the bight of Teervo, there is rather deeper water again, from 11 to 12 feet, and round Coonagh Point the channel winds more to the eastward through what is called the Cross Channel, in which there is not more than eight and nine feet.
A mile and a half above Coonagh Point is Barrington Quay, projecting out to the low-water line, and fit only for boats to discharge at.
Off this quay, a little below it, is a ledge of rocks extending nearly across the channel from the south, consisting of masses of limestone rock, with not more than three feet on them.
The reach between Barrington Quay and Limerick, a distance of rather more than half a mile, is called the Pool; but the general depth is only seven to eight feet at low-water springs, though there are some places with as much as ten feet.
Vessels only lie here preparatory to going alongside the quays or to sailing.
Tides.
Near Limerick, as soon as the flood begins to make, the water rises with sur¬ prising rapidity, frequently in a bore, from its being confined within such narrow limits, and from the constant freshes down the river, the first falls of which occur just above the quays.
During the first hour of the flood there is a rise of as much as seven feet; but after the first quarter, the mud-banks being covered, and thereby affording the water a larger space to flow over, the rise is not so rapid, nor the velocity so great.
This, from the above cause, is always strongest at the first quarter flood and last-quarter ebb.
An extraordinary high water is not always followed by a corresponding very low water,-the cause of either being the wind, which has great Influence over the tides, especially in the narrows.
Thus a strong southerly or westerly wind will keep the \\ ater up in the river, producing a great high water, while it will operate in preventing a great fall; whereas a strong northerly or easterly wind will have precisely the opposite effects.
This cause acts not only on the waters of the river itbelf, but on the sea tides, as a S.
wind drives the flood which comes from the southward into the river, and N.E.
winds drive it off-shore.
There is always a greater rise at the new moon than at full, frequently a foot difference ; also a greater range at the first quarter than the last, and the after¬ noon tide was always the highest during the survey.
The flood stream runs after the turn of tide on the shore during the springs, as much as half an hour; and the ebb sometimes three quarters of an hour, after the flood has made by the shore.
The ebb is always stronger than the flood, the springs varying from 4 * in the narrows to three knots.
At Limerick, it is high water at full and change at 6 h.
16 m.
Rise of springs, 19 feet; neaps, 14 feet.
General Remarks.
The Shannon possesses the great advantage of being easy of access, for, its entrance being broad, free from dangers, and lying latitudmally, vessels may Jboldly.
run for it.
In clear weather the high land of Brandon serves to mark it distinctly, and may be seen.
14 or 15 leagues.
Having made the Loophead
Lighthouse,
