One of the most edifying and interesting exhibitions of illustration art this year is presently on display screen at the Delaware Art Museum., surveys picture from a period of American history that was snapping with energy– a period of music and dance, of flappers and restriction, of the new freedom and permissiveness that came with the car, of the Harlem Renaissance and the literary and visual designings of Vanity Fair. The Delaware show is a robust suggestion of the effectiveness of illustration.