In the month of August 1815, when Sir William Rae, Bart. then Sheriff of the shire of Edinburgh, Mr Robert Hamilton, Sheriff of Lanarkshire, and Mr Adam Duff, Sheriff of Forfarshire, Commissioners of the Northern Light-houses, visited this island, they concurred in judging it highly proper to make special observations on the state of the weather at the Calf Island. In the beginning of November following, the author accordingly sent Mr Macurich, a shipmaster in the light-house service, to that island, with directions to reside there, and make monthly returns of the state of the weather, agreeably to a printed form. During his stay of seven months, it appears, upon the whole, that the fog rested only twice upon the highest land of the Calf, while it cleared partially below. On one of these occasions, I was on board of the Light-house yacht, then at anchor off the island, when the fog was for a time general; and as the weather became clear, I observed that it first disappeared upon the lower parts of the island; and that in half an hour the whole of the Calf was seen. In the journal of the weather alluded to, the Calf Island is represented as often perfectly free of fog, while the higher parts of the opposite mainland of Man, was hid in mist. To account for this, it may be noticed, that the mass of matter in the Calf island is much less, and the land is also much lower, than in the main island. Part of this effect may also be ascribed to the rapidity of the tides, which create a current of wind, particularly in the narrow channel between the Main and Calf islands; which have a direct tendency to clear away the fog; as I have observed at the Skerries in the Pentland Firth , and in similar situations on different parts of the coast, where rapid currents prevail. [Sidenote: ~1816.~] [Sidenote: Distinguishing Light for the Calf of Man.] From these observations, the author was led to report to the Commissioners, that the light-house on the Calf of Man should hold an intermediate position between the highest part of the island, called Bushel’s Hill, and the lower site called Kaager Point; and, further, that by erecting two light-house towers in a certain relative position to each other, they would point out the line of direction of the dangerous sunken rocks called the Chickens, and by adopting that description of light known to mariners as a _Revolving light without Colour_, this station would be sufficiently distinguished from the lights which surround the Isle of Man on the Scotch, Irish, and English shores. [Sidenote: ~1817.~] [Sidenote: Lights of the Isle of Man completed.]