Conceptually speaking, air conditioning has been around since the first primitive humans ducked into cool, damp caves to take refuge from summer heat. But aside from fans of various shapes and sizes, the technology of temperature control didn't progress beyond the stone age until the 1830s. That's when John Gorrie, a doctor from Florida, decided to do something about the stifling heat in his hospital, which he reasoned wasn't doing his malaria and yellow fever infected patients much good. In response, he created a simple contraption that was little more than a fan that blew over a bucket full of ice—and though it was mighty inefficient, it worked.

A more complex device was rigged up in the bedroom of dying president James Garfield in 1881. Naval engineers constructed a kind of box filled with ice water-soaked rags. A fan blew hot air overhead, forcing the cool air to stay low to the floor, where the ailing president's bed was. Half a million pounds of ice and two months later, the president was dead, though the engineers had succeeded in lowering the room's temperature an average of twenty degrees during that time.

But those were experiments, not the norm. Refrigeration first came into common use in some large cities during the late 1800s, typically piped from a central cooling station to meat lockers, keg rooms and even bank vaults where important documents were stored. "Manufactured air," as it was known, was primarily an industrial-use phenomenon until the turn of the century, when men like Willis Carrier, an engineer and air conditioning pioneer, began to experiment with systems practical for use in commercial and residential spaces. The key was precise control of the temperature-humidity relationship in the air, achieved by a series of chilled coils that both lowered temperature and the moisture level. His invention, built for the Brooklyn-based Sackett-Wilhelms Lithographing and Publishing Company, was called the "Apparatus for Treating Air," and it kick-started a revolution.

Suddenly cooled air didn't have to come from a centrally-located supply; any business with enough money could have their own local system. Schools, hospitals, printing plants and textile manufacturers lined up to have air conditioners installed (as well as one wealthy private citizen, Charles Gates of Minneapolis, the first person to have his home—pictured at left—air-conditioned). The thing stopping Carrier's units from going into every home in America, however, was their gigantic size. Further, the potential danger of the toxic ammonia they used as coolant didn't help. In 1922, however, Carrier solved those problems by replacing the ammonia with the relatively safe chemical dielene, and added a compressor to the systems, which reduced their size and expense.

Soon the inventions were popping up in movie theaters all over the country, which became refuges for sweltering cineastes during the summers. Before long, air conditioning was debuting in office buildings, department stores and in fancy trains everywhere. World War II slowed things down a bit since resources were scarce, but when the troops came home and embraced the suburban American dream, many of them wanted that dream air conditioned. Within a few years, window units began selling like hotcakes: from just 74,000 in 1948 to over a million in 1953.

This article was written by Ransom Riggs and excerpted from the mental_floss book In the Beginning: The Origins of Everything. You can pick up a copy in our store.

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