Mount Desert, an island of the state of Maine, at the southern extremity of Hancock co., in Frenchman's bay, about 30 m. S. E. of Bangor; pop. in 1870, 3,935. The island is 14 m. long and 8 m. broad, and has an area of about 100 sq. m. It is divided into three towns, Eden, Mount Desert, and Tremont, and contains 11 post offices, 15 or 20 hotels, 35 school houses, and 6 churches. Ship building and the manufacture of lumber are carried on, and the cod and mackerel fisheries are pursued. A narrow hay or sound runs from the ocean at the S. side of the island into the interior in a northerly direction to the distance of 6 or 8 m. The scenery of the island is very grand and beautiful. The greater part of its surface is covered by seven ridges of mountains, whose highest peak, Mt. Adam or Mt. Green, rises 1,762 ft. above the sea. High up among the mountains are many beautiful lakes, the largest of which is several miles long. The S. E. coast is lined with stupendous cliffs; the most remarkable of these are Great Head and Schooner Head. In Frenchman's bay, on the E. side of Mount Desert, are live high rocky islands called the Porcupines, and about 20 m. to the southward in the open ocean is Mount Desert rock, the site of a noted lighthouse.

Mount Desert is much resorted to in summer for the beauty of its scenery. - The island was discovered and named by the French about the beginning of the 17th century. M. de La Saussaye and Fathers Quentin, Lalemant, Biard, and Masse, with 25 colonists from France, landed here in May, 1613, built a small fort and a few cabins, and called the place St. Sauveur. This settlement was forcibly broken up in a few weeks by Gov. Argall of Virginia. The first permanent settlement was made by Abraham Somes, who in 1761 built a house at the head of the sound.