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 THE LIGHT BULB? Without her, our life would be much more uncomfortable. And there is no home, or car, or bicycle that doesn't use at least one. Let's discover the secrets of the incandescent light bulb and its ... modern granddaughters! The incandescent light bulb is the classic invention that has several fathers. The first father was the British inventor Sir Joseph Wilson Swan who patented it in 1878. It was his home in Gateshead, Great Britain, the first house in the world to be illuminated with electric bulbs . Three years later, in 1881, the Savoy theater in the City of Westminster (London) was the first public building to use incandescent bulbs. The bulb invented by Swan was made of a thick carbon filament which, when heated, emitted light and gas . This idea, however, had some flaws: the inside of the bulb quickly covered itself with so...