Willis Carrier, the inventor of air-conditioning.

What the newspapers did not report was that something had happened involving the second floor of a Brooklyn printing plant – something that changed everything.

What happened was air-conditioning. Sort of. July 17 was the date on blueprints for newfangled equipment to temper the air.

A junior engineer from a furnace company figured out a solution so simple that it had eluded everyone from Leonardo Da Vinci to the naval engineers ordered to cool the White House when President James A Garfield was dying: controlling humidity. It was world-changing.

"Air-conditioning, in the broad sense, had a profound effect on the way people lived and worked," said Bernard A Nagengast, an engineering consultant who specialises in the history of air-conditioning and heating.

"It allowed industry to operate in ways it couldn't operate before, in places it couldn't operate before." "It all but redefined cities and city-states like Singapore, sometimes called the air-conditioned nation," said Eric B Schultz, a former Carrier Corp executive and author of a recently published company history.

And, Schultz said, the Internet, because air-conditioning minimised dust, making possible clean rooms for computer manufacturers and electronics companies.

Carrier Corporation in the 1940s or 1950s, and today. Its second floor was first air-conditioned in 1902.

Window units now dot the exterior of the building.

In time there would be window-mounted air-conditioners to drip on people on the sidewalk below (or fall out and cause injuries). And there would be brownouts in the summer as air-conditioners put a strain on power plants.

But in 1902, there was a printing plant, and a problem.

The plant in Brooklyn had just been completed, Nagengast said. It was built for a company that printed the humour magazine Judge, which carried fanciful illustrations. The printing company had to run each page of the magazine through the press once for each colour on the page. Sometimes one colour was printed one day, and another colour the next.

The problem was that paper would absorb moisture from the sticky Brooklyn air and expand by a fraction of an inch, enough so that the colours would not line up properly.

Worse, he said, "the ink refused to dry fast enough." And the printer could not wait. There was a schedule. There were subscribers who expected the next issue to land in their mailboxes, no matter what.

The junior engineer who tackled the problem was Willis Carrier, who went on to start Carrier Corp. His plan was to force air across pipes filled with cool water from a well between two buildings, but in 1903, he added a refrigerating machine to cool the pipes faster.

A store with air-conditioning, about 1935. The counter-high box next to the cash register is part of the system.

"Carrier was not happy with the pipes," Schultz said, and a couple of years later he had a brainstorm that Schultz called "one of Carrier's essential genius insights," a system that worked far better.

View the original article from The New York Times here.