Mr. Shaw is irritated with the widespread belief that the modern New York subway system has always been associated with the Swiss typeface Helvetica. This misperception was fueled by the attention the typeface received in 2007 on the 50th anniversary of its introduction, especially in Gary Hust wit’s “Helvetica,” a documentary survey of the astonishing ubiquity of a lettering style that appears over the entrances of American Apparel and Staples, on Lufthansa airplanes and New York City garbage trucks, on Comme des Garçons bags, and, yes, on New York subway signs. But the last, as Mr. Shaw shows, was not always so.