David Baron, author of "American Eclipse: A Nation's Epic Race to Catch the Shadow of the Moon and Win the Glory of the World." The book talks about total solar eclipses in general, but focuses specifically on a total eclipse in 1878 that was visible in much of the United States - and which inspired a couple of scientists (one of them a woman) and a young Thomas Alva Edison to organize a special expedition for viewing the eclipse that they hoped would raise the stature of the United States in the worldwide scientific community.