Book excerpt: Everyone knows Dublin's main river, the Liffey. But many people may be less familiar with the Dodder, the Tolka and the Camac. And then there are the 'vanished' rivers, such as the Poddle, which have long been diverted underground. In this fascinating survey of Dublin's waterways, great and small, Clair M. Sweeney guides the reader across the length and breadth of Ireland's capital city, pointing out well-known and lesser-known landmarks, and setting out lore and legend.