In 1935, lava from an eruption of the volcano Mauna Loa, on the Big Island of Hawai’i, started oozing toward the Wailuku River, main source of water for the city of Hilo. This danger to the more than 15,000 residents of Hilo was exactly the opportunity that Thomas Jaggar, founder of the Hawaiian Volcano Observatory, had been waiting for: to blow up a volcano. This isn’t as crazy as it sounds. Actually, no, it was crazy.