GREAT WALL OF CHINA History of the Great Wall of China: The Great Wall of China is the national military defense project in the cold weapon war era with the longest time and the largest amount of construction in the world. It condenses the sweat and wisdom of our ancestors and is the symbol and pride of the Chinese nation. According to historical records, since the Warring States period, more than 20 vassals and feudal dynasties have built the Great Wall. The earliest was the Chu Kingdom. To defend the nomadic or enemy countries in the north, they began to build the Great Wall. Subsequently, Qi, Yan, Wei, Zhao, Qin, and other countries also began to build their own Great Wall for the same purpose. After Qin unified the six countries, the famous emperor Qin Shihuang sent Meng Tian northward to the Xiongnu, connecting the Great Walls of various countries. From Linyao in the west to Liaodong in the east, it stretched for more than 10,...
Who Invented Air Conditioning?
His invention may not have been decisive for the fate of humanity such as that of the wheel or the computer, but on hot days, air conditioning remains one of the products of progress most appreciated by the gasping masses for the great summer heat.
But how was it born? Who was the first to devise a device capable of giving us such coolness?
The aNCESTOR
The first attempts to refrigerate the air of an environment date back to the nineteenth century, when a certain John Gorrie, a medical profession, tried to alleviate the suffering of malaria sufferers. To do this he had installed a rudimentary tool which, blowing on some ice containers hanging on the ceiling, cooled the room air. Subsequently, in 1851, the American doctor improved his "creature" by making a real gas-cooled machine.
But that was an era of inventors and therefore many people took up the idea of Gorrie to build a machine capable of cooling the air on command.
THE HISTORY OF AIR CONDITIONING
The race to create an efficient tool to refresh the rooms was won by the eccentric Willis Carrier.
He was an engineer in an industrial plant factory but was constantly interested in everything around him. According to the testimony of the beloved goddaughter Edna M. Littlehales (Edna was the daughter of a friend of the inventor, but when the man died, it was Carrier who raised the little girl) "uncle Willis" devoted most of his time to to make scientific experiments and observations.
Just following his studies on air humidity, Carrier began working on a system to combat the heat in closed environments. As a young man, he realized the importance of keeping some spaces cool when, working with a color printer, he realized that the heat altered the quality of the photographs.
His invention was to develop a device equipped with two coils of pipes: the first coil contained cold water, the other was run through by chilled water by the evaporation of ammonia. Carrier's invention provided for continuous circulation of the various liquids and therefore the air was dried - that is, deprived of humidity - and cooled even for long periods. It was the first air conditioning!
THE NAME
The term "air conditioning", however, was not from Willis Carrier. It was coined by another American engineer, Stuart Warren Cramer, who spoke about it in 1906, the very year in which our Carrier patented his idea.
COOLING? OK, BUT WITH PARSIMONY ...
Thanks to Carrier's invention (who in 1915 founded a real company for the production of his air conditioners) today air conditioning allows us to work and study in closed spaces without having to drizzle sweat, but this does not mean that we have to abuse it.
Recent studies have in fact shown how the emissions produced by air conditioning systems are harmful to the environment. Therefore, although the new models have already reduced their environmental impact, it would be better to turn on the air conditioner only when the heat is really unbearable.
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