Each 4th of July many of us crowd on rooftops, waterfronts and around televisions to watch the explosive magic of fireworks. Although large, professional pyrotechnic displays are a favorite, some people also enjoy setting off fireworks on their own. This year is the first time since 1909 that New Yorkers in certain counties can legally light fireworks for the Fourth of July (although the change in the law still prohibits New York City residents from putting on their own pyrotechnic shows). Joining us for a Please Explain look at fireworks is journalist and historian Jack Kelly, author of the book Gunpowder: Alchemy, Bombards & Pyrotechnics, and Phil Grucci, CEO of Fireworks by Grucci, which has provided pyrotechnic displays for US presidential inaugurations and will be putting on fireworks shows in 24 municipalities this independence day.