When Franklin was 42 years old, he had already made great achievements in the printing industry and was further obsessed with electricity experiments. He wanted to prove that lightning and static electricity were actually the same. Various experiments held in Philadelphia in 1749 had confirmed that lightning between clouds and between clouds and the ground was electricity; but he still insisted on catching "lightning". He wanted to obtain lightning from storms and store it so that scientists could conduct ordinary research on the ground. So he designed an experimental method for charging in the clouds:

At the top of the tower, a large pavilion that can accommodate people and a simple power station are installed. In the power station, an iron pole is erected, extending out of the pavilion, about 20 or 30 feet high, with a sharp tip. If the pavilion can be kept dry, One person can be placed in the pavilion. When the clouds get lower and there is a sign of a storm, the clouds are full of electricity and sparks, and the iron rod can draw electricity for the people in the pavilion.

Franklin found an excellent insulation method: wax, the material on the iron ring. He even designed a way for the staff to leave the isolation pavilion, so Franklin did understand the dangers of wandering lightning and warned people to protect themselves.

In 1751, the experimental method of the isolation pavilion was published in London. King Louis XV of France encouraged the scientists in the palace to complete this experiment to confirm Franklin's long-held view that lightning and ground electricity are similar! On May 10, 1752, Jean Francois de Aliba (Jean Francois de Aliba) D’Alibard erected a 40-foot-high metal pole with a pointed end on an isolation table in the Marly Garden, 18 kilometers from Paris. The storm quickly enveloped the area. According to Franklin’s description, a man was carefully placed next to the pole, and from time to time he used an insulated iron ring in his hand to absorb lightning and sparks.

The experimental results made Franklin a hero: electricity was obtained from the clouds, stored in a large bottle made of glass and metal (called a Leyden jar), and then used as general electricity in various experiments. This once again confirmed Franklin’s genius!

In the summer of 1952, Franklin Franklin didn't know that his experiment had been a great success in Europe. He was trying to erect a metal pole on the towering spire of the Christ Church in Philadelphia. He believed that in order to absorb lightning, the metal pole must be raised to a considerable height, but the structure of the church spire was too low. Suddenly, Franklin had an idea, that is, a kite equipped with an iron pole.

Franklin made a cross with two wooden sticks, supporting a large piece of satin cloth. This is the legendary immortal kite of Franklin! At the top of the kite, there is a sharp iron wire, and at the end of the wire is tied a metal key. Franklin controls the part of the kite, tied with a secret key. insulator - silk ribbon; when the storm was about to come, the experimenter and his son walked into an open space and built a temporary rain shelter. After the kite rose for quite some time, a thundercloud gradually approached. The following is Prisley's account:

The cloud seemed to have signs of lightning, but it passed by without any movement; but just when they began to feel discouraged about their invention, he noticed several thin lines flashing in the clouds, and then there were signs of uprightness, as if they were directed, appearing one after another! He was shocked by the scene, and quickly stretched out his hand, aiming at the kite in the air. The feat was finally accomplished, and Franklin finally obtained real lightning.

Franklin continued to absorb the sparks from the sky and stored them in the Leyden jar, but there is one key point that must be emphasized here: the lightning did not hit the kite. In fact, this was not Franklin’s original intention. Franklin originally wanted to use the wire to conduct electricity and charge in the clouds. When the electricity was sufficient, he would reach out and let the electrons pass through his body into the ground. Fortunately, Franklin escaped. If the lightning really hit the kite, he might not be able to sign the Declaration of Independence and write "Poor Richard’s Almanac". Almanac).

Franklin's report on the above experiment was published in the Pennsylvania Bulletin on October 19, 1752. In the same article, an article "How to Protect Your Home from Lightning Attacks" was mentioned. This article was later published in the Richard's Almanac in 1753. Franklin believed in the effectiveness of lightning rods. He began to strongly recommend lightning rods in 1751, and the success of the subsequent experiments gave him great confidence in lightning rods: he was sure that it could effectively guide lightning and protect the safety of people's lives and property.

< p>The purpose of this needle is not only to attract lightning, but also to prevent lightning strikes before they happen. This needle can continuously absorb lightning from the sky, and before its intensity is strong enough to form lightning, it can conduct electricity into the ground, just as Franklin described: "When the electricity accumulated in the clouds is released, the fire of lightning will be calmly extinguished into nothingness."

The significance of this isolation booth and kite experiment is not only a pioneering work in the history of electronics, but also very important to the history of the United States. The lightning rod invented in this experiment will save countless lives in the future.