It is evening, near freezing, and fog blankets the Pittsburgh railroad station. A young industrial engineer walks the platform, his brain roiling with a problem that has obsessed him for months. He has gone to sleep with it, awakened to it, and brooded over it while commuting to and from work. Now, while waiting at the station, he paces and paces…and then it strikes–the Archimedean lightning bolt of inspiration. The answer is literally all around him! It is the fog itself!

Subscribe Today

• Did you enjoy our article?
• Read more in American History magazine
• Subscribe online and save nearly 40%!!!
 

The solitary thinker’s name: Willis Haviland Carrier. Few other inventors have had such an impact on American life and yet remained so little-known. For on that foggy night in 1902, Carrier hit upon the theory that became the basis for modern air-conditioning technology–and air conditioning, in a sense, has become the sine qua non of modern American life. The huge postwar population shift from the Northeast and Midwest to the Sunbelt would scarcely have been possible without air conditioning, and scores of technologies from computers to pharmaceuticals could not exist without it. Yet for most of us, the simple ability to cool our homes amid the summer’s heat is more than enough reason to be grateful for Carrier’s fogbound moment of genius.

Carrier, who grew up on a farm near Angola, New York, graduated from Cornell as a mechanical engineer in June 1901. A month later he began work for the Buffalo Forge Company, a firm that produced heating and exhaust systems.

The summer of 1901 was torrid. Sackett-Wilhelms Lithographing and Publishing of Brooklyn became exasperated by how the weather impeded operations–ink dried poorly, colors ran, and paper swelled–and early the following year its executives approached Buffalo Forge, asking if some way could be found to regulate the moisture in the air as well as the temperature. The firm turned to the twenty-five-year-old Carrier, whose research on heating coils had already lopped $40,000 off his employer’s winter heating bill.

For centuries, methods for cooling air had occupied thinkers who ruminated upon the irony that man, who had so early learned to turn cold into warmth, had been so frustrated in doing the opposite. ‘Heat we have in readiness in respect to fire, wrote Francis Bacon at the beginning of the seventeenth century, but for cold we must stay till it cometh or seek it in deep caves and when all is done we cannot obtain it in a great degree. In 1851 two breakthroughs in cooling were achieved: Ferdinand Carré of France designed the first ammonia-absorption refrigerating machine; and in the United States, Dr. John Gorrie patented an ice-making device. Henceforth, the challenge would lay not in lowering temperature but in achieving the second element of the equation–controlling humidity.

Carrier’s partial solution to Sackett-Wilhelm’s problem involved circulating cold water through coils originally designed for heating and then balancing their temperature with the rate of air flow. It worked, and Carrier had every reason to be satisfied. But, while he had fulfilled most requirements for a modern central air-conditioning system, the problem of dew point control remained. It was the solution to this dilemma that came in the Pittsburgh railroad station.

Carrier’s brainstorm was the recognition of a paradox: air could be dried by being saturated with water. He explained it this way: fog is air approximately 100 percent saturated with moisture. The temperature is low, so even though it is saturated, there is not much actual moisture. There could not be at so low a temperature. Now, if I can saturate air and control its temperature at saturation, I can get air with any amount of moisture I want in it. I can do it, too, by drawing the air through a fine spray of water to create actual fog. In effect, the water spray provides a condensing surface for the hot, soggy air passing through it. The moisture condenses on the droplets and drops out, leaving cooler, drier air behind. The patent for Carrier’s Apparatus for Treating Air was granted in the dead of winter–on January 2, 1906.*

Help HistoryNet by bookmarking to