Another revisionist needle in the who-discovered-America rumpus, going apace ever since publication of the Yale-Vinland map in 1965. Enterline, a former computer technologist who quit the field to devote himself entirely to the controversy, has spent the last six years studying early maps and conducting extensive field work in Greenland and Iceland. His findings -- self-proclaimed as revolutionary -- include tentative evidence that the Norse exploration of North America was not limited to isolated incursions by Eriksson but was in fact a continuous process of discovery and settlement (""as far as Alaska"") from approximately 1000 A.D. to the time of Columbus; that Eriksson's successors ""sparked Columbus' voyage"" by communicating geographic information to Europe during this 500-year period; and that the Yale analysis of the Vinland map erroneously located Vinland ("". . . not a land of grapes on the temperate eastern seaboard but a land of pastures in nearly arctic Canada""). These hypotheses -- and at present they remain merely that -- are based on a combination of intelligent speculation, imaginative interpretation of certain cartographic and physical data, and the amateur historian's desire to prove himself right Unlike most recent works on the subject (e.g., Frederick Pohl's The Viking Settlements in North America, p. 54), Viking America is certain to provoke anew the debate over who was here first; and, in the words of Gerald L. Alexander, head of NYPL's Map Division who contributes an enthusiastic foreword, ""If these ideas can withstand the scrutiny of scholars, they will have introduced a wholly unique aspect of Western history."" A companion volume of supportive evidence is in progress.