Air conditioners were originally invented for printing presses.

At the turn of the 20th century, Sackett & Wilhelms Lithographing Company, a printing plant in Brooklyn, New York, had a problem: High humidity was causing its paper to wrinkle, swell, and shrink. As a result, the company was dealing with misaligned prints, jammed equipment, and long drying times. So it called on the heating and fans division of Buffalo Forge Company for a solution.

The task fell to mechanical engineer Willis Carrier, who was head of experimental engineering at Buffalo Forge. Because cold air can hold less water vapor, Carrier focused his efforts on cooling the factory down. Buffalo Forge already manufactured heating coil systems — fans that distribute hot air from steam-filled tubes — to heat buildings, so, Carrier reasoned, why not run cold water through the coils instead?

He installed the first modern air conditioning system in 1902, and his experiment was successful — most home air conditioners function on this same basic principle. But the system didn’t operate on the level that Sackett & Wilhelms needed it to. So Carrier got to work on something that could actually meet the needs of a large factory, and developed the first spray type air conditioner, a large enclosure filled with water nozzles that could cool hot air before sending it back into the factory. The cool air, even though it came from a wet environment, could hold less water, so it successfully reduced the overall humidity.

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