January 9, 1793: French aviation and ballooning pioneer, Jean Pierre Blanchard makes the first successful balloon flight in the United States. The hydrogen-filled balloon took off from Philadelphia, soared to 1,700 metres and eventually landed 24 kilometres away, in Woodbury, New Jersey. His only passenger was a small black dog. The ascent was witnessed by George Washington, Thomas Jefferson, Henry Clay, Paul Revere, John Adams and other dignitaries. His account, Journal of my forty-fifth ascension, being the first performed in America, on the ninth of January, 1793 is available online on the Internet Archive website, http://www.archive.org.
January 9, 1816: A safety lamp invented by Sir Humphry Davy is tested  for the first time in a coal mine at Hebburn Colliery in north-east England. At the time there were often underground explosions caused by methane leaking out of the coal seams being ignited by the flame of a miner's lamp. Davy determined that placing fine wire gauze around the flame would prevent this from happening. He calculated that the diameter of the holes in the gauze should not exceed 1/22 inch and that the thickness of the wire should be between one fortieth and one sixtieth of an inch. Since the flame changed colour in the presence of methane it also served as an early warning system.