a fortified town and royal dockyard on the Medway (which at Rochester bridge is a considerable tidal river), Kent, 30 miles from London. It includes the village of Brompton, between which and Rochester it forms a continuous, narrow, and irregular street. The houses are ill-built, many of them being only of wood. It contains two Established and seven Dissenting churches, five schools (including a ragged school), and a mechanics' institute. Its charities included several ancient hospitals, which have now been superseded; but there is still maintained a military lunatic asylum and several smaller establishments. The "Chest," for disabled seamen, established by Queen Elizabeth, who also founded the dockyard, has been removed to Greenwich. An account of the dock will be found under the article Dockyard. Chatham returns one member to the imperial parliament. Pop. (1851) 28,424.