Legendary cartoonist Bill Griffith’s new graphic biography of his great-grandfather, William Henry Jackson

You may know cartoonist Bill Griffith from his iconic character Zippy the Pinhead, who made the leap from underground comic books to mainstream daily newspaper comic strips. But Griffith has made a late-career turn to become a graphic biographer, notably with his innovative and entertaining biography of cartoonist Ernie Bushmiller: Three Rocks: The Stor…