a river of England, which runs through the counties of Lancaster, York, and Chester, and empties itself into the Irish sea at Liverpool. By means of inland navigation, it has communication with the rivers Dee, Ribble, Ouse, Trent, Derwent, Severn, Humber, Thames, Avon, &c.; which navigation, including its windings, extends above 500 miles, in the counties of Lincoln, Nottingham, York, Lancaster, Westmoreland, Chester, Stafford, Warwick, Leicester, Oxford, Worcester, &c.

MERSEY Island, an island of Essex, at the mouth of the Coln, south of Colchester. It was seized by the Danes in the reign of King Alfred, for their winter quarters. It had eight parishes, now reduced to two, viz. East and West Mersey. There was formerly a blockhouse on the island.