The rolling wheels of Canada's mobile libraries carry the magic of books down long, dusty roads, across swift-flowing rivers, through winding, green valleys, over rocky mountain passes. In the Peace River area of northern British Columbia, librarian Howard Overend ranges over 110,000 square miles. Three times a year he takes thousands of books to 60 schools, 28 rural communities, isolated oil and construction crews. Packed in boxes aboard the branch library's van (a real shelf-lined bookmobile is yet to come), the books are carried into country schoolhouses, village stores, or just set on the ground. In such places as Sunset Prairie, Doe River and Upper Cutbank, children and their parents crowd around the boxes, make selections, give thumb-nail reviews, make known their preferences for the library's next visit. Inevitably, there are the hazards of the road: snow, ice and 40-below zero temperatures, the choking dust of mid-summer, the treachery of river ice during spring break-up. All these hamper but do not deter the Peace River Block's roaming, all-weather library.