On examining Plate II., it will be seen that what I have hitherto denominated the Skerryvore Reef, is a tract of foul ground, consisting of various small rocks, some always above the level of the sea, others covered at high water, and exposed only at low water, and others, again, constantly under the surface, but on which the sea is often seen to break after heavy gales from the westward. This cluster of rocks extends from Tyree in a south-westerly direction, leaving, however, between that island and the rock called Boinshly, the first of the great Skerryvore cluster, a passage of about five miles in breadth, and having a depth of thirteen fathoms at low water of spring tides, but not without hidden dangers, which line the rugged shores of Tyree from Kennavarah to Ben Hynish, and some of which lie farther off than might be expected. This passage is called the passage of Tyree; but it is by no means safe during strong and long continued gales, as the sea which rises between Tyree and Skerryvore, is such that no vessel can _live_ in it. I have myself often seen it one field of white broken water, the whole way from Tyree to the Rock; and we know that the wreck of the Majestic, which occurred in 1841, during the progress of the works, was entirely caused by the heavy seas which she encountered off Boinshly. * * * * * The principal rocks of the group, are called Boinshly, Bo-rhua, and Skerryvore, while those lying to the westward, which have been more recently laid down, have received the names of Mackenzie, Fresnel, and Stevenson. * * * * *