1758 All liquid evaporation has a cooling effect. Benjamin “I invented everything” Franklin and Cambridge University professor John Hadley discover that evaporation of alcohol and other volatile liquids, which evaporate faster than water, can cool down an object enough to freeze water.
1820 Inventor Michael Faraday makes the same discovery in England when he compresses and liquifies ammonia.
1830s At the Florida hospital where he works, Dr. John Gorrie builds an ice-making machine that uses compression to make buckets of ice and then blows air over them. He patents the idea in 1851, imagining his invention cooling buildings all over the world. But without any financial backing, his dream melts away.
1881 After an assassin shoots President James Garfield on July 2, naval engineers build a boxy makeshift cooling unit to keep him cool and comfortable. The device is filled with water-soaked cloth and a fan blows hot air overhead and keeps cool air closer to the ground. The good news: This device can lower room temperature by up to 20 F. The bad news: It uses a half-million pounds of ice in two months… and President Garfield still dies.
1902 Willis Carrier invents the Apparatus for Treating Air for the Sackett-Wilhelms Lithographing and Publishing Co. in Brooklyn, N.Y. The machine blows air over cold coils to control room temperature and humidity, keeping paper from wrinkling and ink aligned. Finding that other factories want to get in on the cooling action, Carrier establishes the Carrier Air Conditioning Company of America.