Weather Wise

IF IT were not for a wonderful invention patented 96 years ago, much of the south-east of the United States, including Florida, Alabama, Georgia and the Carolinas, would have remained wilderness, alligator swamp and farmland, instead of being home to some of the most rapidly growing cities in the Union, such as Miami and Atlanta.

All this is down to one man, Willis Haviland Carrier. Like the invention of the elevator, which made the skyscraper possible, Carrier's brainwave - air conditioning - allowed the urbanisation of the Deep South, a place with a truly nasty summer climate - combining very high temperatures and humidity.

Carrier's first patent, for "an apparatus for treating air'', was filed in 1902. Attempts at air-conditioning had been made before, but as these involved huge quantities of ice that had to be replaced, they were far from practical. Carrier's machines worked on the same principle as the refrigerator, compressing gases with a pump, and allowing them to expand, taking heat from their surroundings.

Initially, only industry was interested in his idea. Carrier's first customer was a Brooklyn printing company, which was having problems in the summer with its colour dyes. But soon the value of aircon was realised, and it was reported that "patrons exclaimed with delight when they got through the doorway'' of a newly air-conditioned Texan theatre. Department stores and businesses found they could increase sales and productivity by keeping cool, and by the Fifties aircon was common in homes and cars across the country.

Thanks to the ubiquity in the US of Carrier's invention, few Americans would tolerate the sticky and unpleasant conditions still commonly found in British offices, schools, cars and homes in July and August.