Willis Haviland Carrier had done it! On July 17, 1902, this youngster with a Master's in Engineering degree in hand from Cornell University completed the first schematic drawings of what was to be the first modern-day air conditioners (AC).

But back then, human comfort was the last thing on this American engineer's mind because he was confronted with a problem brought to him by Sackett & Wilhelms, Brooklyn, New York. Humidity was wreaking havoc on their printing processes — the paper seemed to be expanding, contracting and doing humidity's bidding.

So what Carrier came up with was this: Air was forced through a piston-driven compressor and pumped over coolant-chilled coils. Then the air made its way out where it would cool down the surroundings. Piston power was replaced with a centrifugal chiller and ammonia, the cooling agent, was also replaced eventually.

Soon, the engineer started his own company, Carrier Engineering Corp, and would supply these ACs to hotels, theaters, stores and beyond. Yes, the same company still exists and continues to be one of the biggest players in the market.

Would you believe that as a child, Carrier would struggle with fractions? It was his mother who used an apple to simplify the task. He is known to have said, "She educated me. Fractions took a new meaning and I was very proud. No problems would be hard for me after that. I would simply break them into something simple and then would be easy to solve. ”