On this day, we can all give thanks to Willis Carrier, inventor of air conditioning:

In 1906, Carrier discovered that "constant dew-point depression provided practically constant relative humidity," which later became known among air conditioning engineers as the "law of constant dew-point depression." On this discovery he based the design of an automatic control system, for which he filed a patent claim on May 17, 1907. The patent, No. 1,085,971, was issued on February 3, 1914.
On December 3, 1911, Carrier presented the most significant and epochal document ever prepared on air conditioning – his "Rational Psychrometric Formulae" – at the annual meeting of the American Society of Mechanical Engineers. It became known as the "Magna Carta of Psychrometrics." This document tied together the concepts of relative humidity, absolute humidity, and dew-point temperature, thus making it possible to design air-conditioning systems to precisely fit the requirements at hand.
With the onset of World War I in late-1914, the Buffalo Forge Company, for which Carrier had been employed 12 years, decided to confine its activities entirely to manufacturing. The result was that seven young engineers pooled together their life savings of $32,600 to form the Carrier Engineering Corporation in New York on June 26, 1915.

Carrier descended from deep Yankee stock, including an ancestor who refused to confess to witchcraft:

The first Carrier in America was Thomas, who arrived in Massachusetts around 1663. There is historical evidence that Thomas was born in Wales in 1622 and that he was a political refugee who assumed the name "Carrier" upon coming to America.[6] Thomas married Martha Allen, daughter of Andrew Allen, a first settler of Andover, MA. After standing up against the Andover town fathers in a boundary dispute, she was accused of being a witch. Two of her sons, aged 13 and 10, were hung by their heels until they, too, testified against her. Cotton Mather denounced her as a "rampant hag" whom the Devil had promised "should be the queen of Hell." She was arrested, convicted and, on August 19, 1692, hanged on Salem's Gallows Hill. Later it was recorded that of all the New Englanders charged with witchcraft, "Martha Carrier was the only one, male or female, who did not at some time or other make an admission or confession."

The lineal descent from a woman hanged for witchcraft (and boldly refusing to confess) to a brilliant scientific mind that made such a vast contribution to human progress is a wonderful expression of the triumph of science and reason.

Stay cool!