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Who Invented Air Conditioning?

air conditioners, ac
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Who hasn't sung the praises of air conditioning on a sweltering summer day? But who do you have to thank for this refreshing convenience?

The short answer to that question is Willis Carrier, an American engineer credited with inventing the first modern air conditioner. However, the idea of using evaporated water — or other liquids — to cool off a muggy space far precedes Carrier's 1902 invention.

Ancient AC

The first known systems that used water to cool indoor spaces were created by the ancient Egyptians, who lowered the temperature in their homes by hanging wet mats over their doorways. The evaporated water from the wet mats reduced indoor air temperatures and added refreshing moisture to the dry desert air.

Not long after the Egyptians beat the heat with their doorway mats, the Romans developed a primitive air conditioning system by utilizing their famous aqueducts to circulate fresh water through indoor pipes, a method that significantly reduced the air temperature inside stuffy villas.

Cool experiments

Of course, it wasn't until long after the Romans had their time in the sun that the principles of modern air conditioning were developed. In 1758, American statesman and inventor Benjamin Franklin, along with John Hadley, a professor at Cambridge University, began experimenting with the refrigerating effects of certain liquids.

In previous studies, Franklin had determined that the refrigerating effects of a liquid are related to how quickly it evaporates. He and Hadley expanded on this finding by using ether and a bellows to cool down a mercury thermometer to 25 degrees below freezing. This experiment prompted Franklin to remark in his journal about the possibility of freezing to death, even on a warm summer's day.

This observation by Franklin was a foreshadowing of things to come. In 1820, British inventor Michael Faraday was also experimenting with the refrigeration properties of gases when he discovered that, by compressing and liquidizing ammonia and then allowing it to evaporate, he could cool the air inside his laboratory.

Modern air conditioning is born

Several decades after Faraday made his discovery with ammonia, a Florida physician named John Gorrie developed a machine to keep yellow fever patients cool. Gorrie's machine used compressed air and water to create an open cooling system. Patented in 1851, Gorrie's "cold air machine" was the first patented invention that facilitated mechanical refrigeration, as well as the first to resemble a modern air conditioner.

But it wasn't until 1902 that the history of air conditioning really began to heat up. In that year, a young engineer named Willis Carrier was tasked with the chore of creating a system for treating the air at the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, N.Y. Printing company executives found that excessive humidity at its printing plant wreaked havoc on the color register used for fine, multi-color printing.

By 1903, Carrier had designed a system of chilled coils that maintained a constant, and comfortable, humidity of 55 percent inside the Sackett-Wilhelms printing plant — the equivalent of using 108,000 pounds of ice daily to cool the plant. The modern air conditioner was born. [See also: Science of Summer: How Does Air Conditioning Work?]

Not long after Carrier invented his game-changing air conditioning machine, a mill engineer named Stuart Cramer created a similar ventilating device to add water vapor to the stifling air inside of textile plants. While Cramer was the second person to develop such a device, he was the first to coin the term "air conditioning" to describe the purpose of his invention.

Air conditioning continued to be used in plants and mills throughout the early 1900s, but it wasn't until 1914 that this modern convenience was installed for the first time in a private home. In that year, a Minneapolis millionaire named Charles Gates hired Carrier to install an air conditioner in his mansion.

By the 1920s, scores of commercial businesses jumped on the air conditioning bandwagon, installing huge (by modern standards) and toxic (they used ammonia as a coolant) air conditioning devices in their stores. The expansion of air conditioning into American homes was stalled during the Great Depression and World War II, but by the 1950s, those who could afford it began adopting this modern convenience by the thousands.

Follow Elizabeth Palermo on Twitter @techEpalermo, Facebook or Google+. Follow LiveScience @livescience. We're also on Facebook & Google+.

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