This new book sets its small horizontal island mills within the social and historical life of the island. It seeks to answer where these mills may have come from, given that their every part is to be found in horizontal mills in many countries in Europe and beyond. Were they, for example, introduced by Viking settlers – hence their being named Norse Mills – or were they brought at an earlier period by Celts from Ireland where there is concrete evidence of their early use? The book contains a detailed gazetteer of over 250 sites where mills were once worked throughout the island, along with a map reference for each and a simple grading of the condition of the sites. Almost all these sites are ruins of the former mill building and lade. The book is extensively illustrated with pen and ink drawings and a range of photographs and other images.