SOMME, a department in France, is bounded N. by that of Pas-de Calais, E. by Nord aud Aisne, S. by Oise, and W. by the new depart ment of Seine.Marititne and the English Channel. Its greatest length, from the neighbourhood of Ham to the mouth of the Seine, is about 80 miles ; the greatest breadth, from the Bresle near Atimale to the neighbourhood of Lucheux, is 47 miles. The area is 2373'4 square miles. The population in 1811 was 559,630; in 1851 it was 570,611, giving 239.92 inhabitants to a square mile, or 65'34 above the average per square mile for the whole of France. The department is formed out of the old Picard districts of Amienais, Santerre, Ponthieu, and a part of Vermandois, which had Amiens, Peronne, Abbeville, and Ham respectively for their chief towns.
The surface of the department is generally level, in parts undulating and billy. The coast, which runs nearly due north and south, is divided into two nearly equal parte by the testuary of the Somme; to the north of that river the shore is lined by sand-hills or downs, which protect the low grounds from the incursions of the sea ; to the south of the Somme commence the cliffs which extend along the coast to the neighbourhood of Havre. The coast-line has undergone a considerable change even in comparatively recent times. In the 9th century the waves the low ground between the Somme and the Authie, several miles inland from the present shore. When the sea retired there remained for some time a large lake, long since dried up, the site of which forms one of the moat fertile districts in the department. The whole of the department is occupied by the formations of the cretaceous group. The exteneive chalk-plains are intersected at inter vals by valleys, watered by streams, and presenting green meadows and trees, which contrast favourably with the general nakedness of the cuuutry. Some sandstone for paving is quarried, and peat is dug in some of the valleys.
The department is watered by the Somme and its tributaries, and by the Bresle and the Authie. The Somme rises in the department of
Aisne, not far from St-Quentin; it has first a south-western course for about 18 or 20 miles, and enters this department just above the town of Ham, below which it flows about 20 miles to the north-north west to C1617, below P6ronne, and thence westward 30 miles to Amiens. Below Amiens its course is north-west in a tolerably direct line, past Abbeville, 45 miles to the sea. Its whole course is about 115 miles, 95 miles of which are iu this department. Vessels of 150 tons and small steamers ascend the river as far as Abbeville; and bargee of 40 to 50 tone ply between Abbeville and Amiens. By means of lateral eanaliettion, and the improvement of the bed of the river, the Somme has been made navigable from Amiens almost to its source. By means of this lateral canal a communication is opened into the canal of St.-Queutin, which used to be called the Angoulatue Canal, and thus a communication is formed with the Escaut or Schelde, the Oise, and the Seine. [Arms] The priucipal feeders of the Somme are the Miraumont, the Nieve, and the Male, on the right bank ; and the Ayre, which receives the Dam or Don and the Noye, and the Celle, on the left bank. These are all small ; but the Ayre has been made navigable for about 12 miles. The Authie rises not far from Doulleos, and flows past that town in a north-west direction into the sea. It separates the department from Pits-de-Calais. The Bresle risen in the department of Oise, and flows north-went into the sea between this department and Seiue-Maritima. Neither the Authie nor the Bresle is navigable; but the mouth of the latter forms the harbour of Treports LSEINE.I N FkItIEURF..] The department is traversed by 10 imperial, 8 departmental, and a great number of communal roads ; and also by railroads from Amiens to Paris, Boulogne, and Lille. A railway has been recently authorised to be made from Amiens to Rouco through Gournay.