It seems fitting to be writing about two Irish bestsellers on St. Patrick's Day. Marking its second week on the hardcover chart is Frank Delaney's Ireland, which traces Irish history from prehistoric times to the country's struggle for independence. HarperCollins has gone back to press five times, taking the 55,000-copy first printing to 100,000. Delaney was interviewed on NPR's Weekend Edition by Scott Simon, who read the book months ago, on the recommendation of a London driver. Edward Rutherfurd's 2004 hardcover bestseller, The Princes of Ireland (on the hardcover charts for seven weeks), has 130,000 copies in the Ballantine trade paper edition.