According to the Book of Jin Lu Ji Biography, Lu Ji, a great poet in the early Jin Dynasty, kept a dog named Huang Er, which was very popular with his master. Lu Ji lives in Luoyang, the capital of Beijing, and misses his hometown in Jiangnan very much. One day, he joked to Huang Er, I haven't been able to communicate with my family for a long time. Can you deliver the message for me? I don't want the dog to wag its tail and make noises over and over again, as if it agreed. Lu Ji was surprised and immediately wrote a letter, put it in a bamboo tube, tied it around Huang Er's neck, and let it out. Huang Er not only sent the letter to Lu Ji's home, but also brought back a reply from his family. Later, Huang Er often traveled all over the country, delivering letters for Lu Ji and becoming a dog messenger.
Communication Tower/KLOC-In the 0/8th century, French engineer Claude Chapp successfully developed a practical communication system to speed up information transmission. The system consists of several communication towers, which are built 230 kilometers between Paris and Lille. A wooden pole is erected at the top of these towers, and a horizontal crossbar is installed on the wooden pole. People can rotate and swing the wooden pole under the operation of ropes to form various angles. The two vertical arms are installed at both ends of the horizontal cross bar and can also rotate. In this way, each tower can form 192 different configurations through wooden poles, and the nearby towers can see the information representing the meaning of 192 through telescopes. In this way, within a distance of 230 kilometers, the information can be transmitted in two minutes. This system made great contributions to the French revolutionary war in the18th century.
For more than 400 years, signal flags have been used for communication on ships. The advantage of banner communication is very simple. Therefore, even today when modern communication technology is quite developed, this simple communication mode is still preserved and becomes an important way of short-distance communication. In sign communication, signal signs can be used alone or in combination to express different meanings. Usually hanging a flag indicates the most urgent, important or commonly used content. For example, the A-flag is hoisted, which means "There are divers under my boat, please stay away from my boat slowly"; Hang the O-flag, which means "someone falls into the water"; Hanging the W flag means "my ship needs medical assistance" and so on.
During the 200 years of15-16th century, the commander of the fleet commanded his ships by firing guns or sailing. 1777, Admiral Howe, commander of the British and American fleets, printed a signal manual, becoming the first person to write a signal book. Later, Admiral Sir Popham used some flags as shorthand letters to create a complete set of semaphore letters. 1805, when Lord Nelson commanded the Battle of Trafalgar, the last signal he sent before he died was 16 Pophanqi: "Close to the enemy and fight at close range." 18 17, the British navy colonel Mariette compiled the first internationally recognized alphanumeric. There are also 40 signal flags, including 26 letter flags, digital flags 10, 3 substitute flags and answer flags 1. Flags have different shapes: dovetail, rectangle, trapezoid, triangle and so on. The colors and patterns of flags are also different.