Orne, a department of the north-west of France, about half of which formerly belonged to the province of Normandy and the rest to the duchy of Alengon and to Perche. Pop. (1906) 3 1 5,993. Area, 2371 sq. m. It is bounded N. by Calvados, N.E. by Eure, E. and S.E. by Eure-et-Loir, S. by Sarthe and Mayenne and W. by Manche. Geologically there are two distinct regions: to the west of the Orne and the railway from Argentan to Alengon lie primitive rocks connected with those of Brittany; to the east begin the Jurassic and Cretaceous formations of Normandy. The latter district is agriculturally the richest part of the department; in the former the poverty of the soil has led the inhabitants to seek their subsistence from industrial pursuits. Between the northern portions, draining to the Channel, and the southern portion, belonging to the basin of the Loire, stretch the hills of Perche and Normandy, which generally have a height of from Soo to 1000 ft. The highest point in the department, situated in the forest of Ecouves north of Alengon, reaches 1368 ft. The department gives birth to three Seine tributaries - the Eure, its affluent the Iton, and the Risle, which passes by Laigle. The Touques, passing by Vimoutiers, the Dives and the Orne fall into the English Channel, the last passing Sees and Argentan, and receiving the Noireau with its tributary the Vere, which runs past Flers. Towards the Loire flows the Huisne, a feeder of the Sarthe passing by Mortagne, the Sarthe, which passes by Alengon, and the Mayenne, some of whose affluents rise to the north of the dividing range and make their way through it by the most picturesque defiles. The department, indeed, with its beautiful forests containing oaks several centuries old, its meadows, streams, deep gorges and stupendous rocks, is one of the most picturesque of all France. In the matter of climate Orne belongs to the Seine region. The mean temperature is 50 F.; the summer heat is never extreme; the west winds are the most frequent; the rainfall, distributed over about a hundred days in the year, amounts to 36 in. or about 5 in. more than the average for France.
Horse-breeding is the most flourishing business in the rural districts; there are three breeds - those of Perche, Le Merlerault and Brittany. The great government stud of Le Pin-au-Haras (established in 1714), with its school of horse-breeding, is situated between Le Merlerault and Argentan. Several horse-training establishments exist in the department. A large number of lean cattle are bought in the neighbouring departments to be fattened; the farms in the vicinity of Vimoutiers, on the borders of Calvados, produce the famous Camembert cheese, and others excellent butter. The bee industry is very flourishing. Oats, wheat, barley and buckwheat are the chief cereals, besides which fodder in great quantity and variety, potatoes and some hemp are grown. The variety of production is due to the great natural diversity of the soils. Small farms are the rule, and the fields in those cases are surrounded by hedges relieved by pollard trees. Along the roads or in the enclosures are planted numerous pear and apple trees, the latter yielding cider, part of which is manufactured into brandy. Beech, oak, birch and pine are the chief timber trees in the extensive forests of the department. Orne has iron mines and freestone quarries; a kind of smoky quartz known as Alengon diamond is found. Its most celebrated mineral waters are those of the hot springs of Bagnoles, which contain salt, sulphur and arsenic, and are employed for tonic and restorative purposes in cases of general debility. In the forest of Belléme is the chalybeate spring of La Hesse, which was used by the Romans.
Cotton and linen weaving, principally carried on at Flers (q.v.) and La Ferte-Mace (pop. 4355), forms the staple industry of Orne. Alengon and Vimoutiers are engaged in the production of linen and canvas. Vimoutiers has bleacheries, which, together with dye-works, are found in the textile centres. Only a few workmen are now employed at Alengon in the making of the lace which takes its name from the town. Foundries and wireworks also exist in the department, and articles in copper, zinc and lead are manufactured. Pins, needles, wire and hardware are produced at Laigle (pop. 4416), and Tinchebray is also a centre for hardware manufacture. There are also glass-works, paper-mills, tanneries (the waters of the Orne being reputed to give a special quality to the leather) and glove-works. Coal, raw cotton, metals and machinery are imported into the depart ment, which exports its woven and metal manufacture, live stock and farm produce.
The department is served by the Western railway. There are four arrondissements, with Alengon, the capital, Argentan, Domfront and Mortagne as their chief towns, 36 cantons and 512 communes. The department forms the diocese of Sees (province of Rouen) and part of the academie (educational division) of Caen, and the region of the IV. army corps; its court of appeal is at Caen. The chief places are Alengon, Argentan, Mortagne, Flers and Sees. Carrouges has remains of a château of the 1 5th and 17th centuries; Chambois has a donjon of the 12th century; and there is a fine Renaissance château at O. A church in Laigle has a fine tower of the 15th century. There are a great number of megalithic monuments in the department.