142 Proceedings oj the Royal Irish Academy. 



off the eastern shore at a distance of about 2 miles, and are about tbe 

 same distance apart. This outer coast has a veiy shallow sea-board, 

 with numerous low sunken rocks, and being much exposed is 

 dangerous to navigation. These islands are the most eastern limits of 

 land comprised in the Irish survey. 



"Along the western margin of Sti'angford Lough, the largest 

 islands are to be found, viz.. Islands, Taggart, !More, 3Iahee, and 

 Eeagh, while many smaller ones are thickly dispersed all round. 

 Extensive sandy and slob-lands occur sui'rounding these, the islands 

 themselves being composed chiefly of rounded di-ift-hills, tailing off 

 down to the water's edge. Some of these, on theii' exposed side, end 

 abruptly in a steep escarpment, sometimes on the northern, and at 

 others on the southern side. On none of these does rock i^i situ occui', 

 while on those along the eastern side, the margins of the islands are 

 formed of solid rock, with a central coveiing of drift. Strangford 

 Lough is connected with the sea by a naiTow strait about 5 miles 

 long, and from half to three-quarters of a mile in average width." 



fp. 12.) — " IS'ear its exit occurs Rock Angus and several isolated 

 rocks ('Pladdies') of a dangerous nature, and upon the bar (on 

 which is always deep water) at times, a terrible sea breaks. 

 Thi'oughout the strait, a wide and deep channel exists, attaining a 

 depth 26 fathoms off the Cloghy rocks, and 35 fathoms (or 216 

 feet) between Portancarlagh and Ballyhenry Bay. This strait has 

 mostly rocky shores, and is kept clear by the scouring action of the 

 tides, which here run with a veiy rapid current, at about 5 to 7^ 

 knots an hour for ordinary tides, and up to 9 knots for some spring 

 tides. In parts, the passage is contracted to comparatively small 

 dimensions, the naiTowest being between Isle-o'-Valla and Rue Point 

 on Bankmore Hill, where it is only 1700 feet wide. This latter side 

 being an obstruction of a projecting drift hill, is gradually wearing 

 away, thus tending to widen the channel of this place. A little 

 south of this, between Black Islands and Gowland Rocks, at low water, 

 the passage is reduced to only 1000 feet, with a depth of 15 fathoms. 

 Here there is a whirlpool. About half a mile to the southward occurs 

 also a series of whirlpools of considerable size, where there is a depth 

 of 26 fathoms, whose influence is felt for upwards of half a mile, and 

 which are called ''the Routen Wheels." Here a bad sea always 

 prevails, and small vessels even hesitate to pass through them except 

 at slack water. The roaring of these breakers is often heard for many 

 miles distant. It is probably to some iiTegular or peculiar conforma- 

 tion of the bottom, with the rapid cun'ent flowing over it. that these 



