opposite shores of the Kingdom, seems to imply the universality of this phenomenon in the British Seas; and the position of Skerryvore would lead to the belief, that it is not confined to narrow seas, but that it exists in the ocean. I cannot dismiss the subject of the survey, without mentioning the late Mr James Ritson, who acted as principal assistant surveyor, and to whose zeal and intelligence so much of its accuracy is to be attributed. The deep gulley which intersects the main Rock from N.E. to S.W., and across which he one day sprang while it was filled with a breaking wave, bears his name, as a memorial of his activity and perseverance. At the close of the survey in 1835, the station-pole was left wedged and batted into one of the fissures or crevices of the Rock, and a cask of water was firmly _lashed_ to ring-bolts in a cleft of the highest part of the Rock, in the hope that it might possibly prove useful to some shipwrecked seamen. [4] _Vide_ Stevenson’s Marine Surveying and Hydrometry. Edinburgh, 1842, p. 144. * * * * * For the purposes of navigation generally, a survey merely indicating the position and extent of the foul ground would have been sufficient. But in connection with the work which was about to be commenced, it was particularly desirable to have exact details of the depths, rocks, and shallows of the surrounding sea, with the nature of the bottom, accurately laid down; and our experience during the course of the work, more than once shewed how essential was the possession of minute topographic information to the safety of the shipping attending the works; more especially as some of the vessels lay very near the rocks, and were frequently driven, by a sudden change of wind, to seek shelter, during the darkest nights, among the neighbouring islands. * * * * *