an arrondissement of the department of the Seine and Oise, in France. It extends over 856 square miles, comprehending five cantons and 127 communes, with 59,720 inhabitants. The capital is the city of the same name situated on the left bank of the river Seine. It is well built, and has a bridge over the river, an ancient collegiate church, and some pleasing promenades. Near to it is Rosny, the birth-place of the celebrated Sully the minister and historian. It contains 588 houses, and 3850 inhabitants. Long. 1° 35'. E. Lat. 48° 58'. N.