MEDWAY (the ancient Vaga), a river of England, which rises in the S.E. of the county of Surrey, near East Grinstead, flows in a winding N.N.E. direction across the county of Kent, and joins the Thames by a broad estuary at Sheerness. It passes Tunbridge and Maidstone, and becomes at Rochester and Chatham a tidal stream of great depth, spreading out into a broad estuary, and forming an important harbour for the British navy. It is 60 miles in length, for more than 40 of which it is navigable.