SKEHRYVORE is the chief rock of a reef which lies about 10 m, s.s.w. of the s.w. point of the island of Tiree (q.v.), and 24 m, w. of Iona. This reef, which stretches from 8 to 10 in. in a w.s.w. direction, is composed to compact gneiss, worn smooth by the constant action of the waves, and was long a terror to mariners, having caused the loss of one ship annually for forty years previous to 1844. The northern light-house eom mission had long intended the erection of a light-house on Skerryvore, the only point of this dangerous reef which could afford the needful foundation; but the difficulty of landing on the rock, from the immerse force (three tons to the superficial foot) with which the Atlantic waves beat upon it. caused the delay of the scheme till 1834, when preparations were made in earnest. The design and superintendence of the construction of the building were intrusted to Mr. Alan Stevenson, who commenced operations oil
the rock in 1838. following generally the mode adopted by his father. Mr. Robert Ste venson (q.v ), in the construction of the Bell rock (q.v.) light-house; and, in spite of occa sions] disasters from tempests. completed his work in 1844. The light-house is 138} ft. high; at the base 42 ft.. and at the top 16 ft. in diameter. The light, a revolving one, is produced by the revolution of eight large annular lenses round a lamp of four wicks, according to Fresnel's first dioptric system, and can be seen at a distance of 18 miles. The costof erection was close upon ,e87,000. Skerryvore light-house is nearly s higher than that on the Bell rock, and more than twice as high as the Eddystone. A small' group of rocks belonging to this reef, and situated 3 m. westward of the light-house, is known as Stevenson's rocks.