Perhaps most widely known as publisher of the mass-circulation, general-audience picture magazine Look, Gardner ("Mike") Cowles, Jr., was chief executive officer of a media conglomerate that included newspapers, book publishing, and broadcast outlets as well as several magazines. In newspaper journalism Cowles pioneered the use of opinion polling in the 1920s, when he hired George Gallup to do readership surveys for the Des Moines family-owned newspapers. In the late 1920s he introduced to the Register a series-photograph technique for the Sunday rotogravure section. (Most roto sections of the time ran single news items or feature shots of events.) The success of these picture series generated a syndicated-photo company and inspired Cowles to begin Look in the late 1930s. He and his older brother John expanded the family's holdings from those in Des Moines to others in Minneapolis and New York and, at their peak, included examples of almost...