How did Franklin invent the lightning rod?

At the age of 42, Franklin had made great achievements in the printing industry and was further fascinated by electrical experiments. He wants to prove that lightning and static electricity are actually the same. Experiments held in Philadelphia from 65438 to 0749 have confirmed that lightning between clouds and between clouds and the ground is electricity; But he still insisted on catching lightning. He wants to get lightning from the storm and then store it so that scientists can do ordinary research work on the ground, so he designs an experimental method of charging between clouds:

At the spire, a large-capacity pavilion and a simple power station were installed. In the power station, an iron bar is erected, stretching out of the pavilion, about twenty or thirty feet high and sharp at the tip. If the pavilion can be kept dry, there can be a person in it. When the clouds become low, there are signs of a storm. At this time, the clouds are full of abundant electricity and sparks, and the soldering iron can draw electricity for the people in the pavilion.

Franklin discovered an excellent insulation method: wax, the substance on the iron ring. He even designed a way for the staff to leave the isolation booth, which made Franklin really understand the danger brought by stray lightning and warned people to protect themselves.

175 1 year, the experimental method of isolation booth was published in London. King Louis XV of France encouraged the scientists in the palace to complete this experiment to confirm Franklin's persistent view that lightning and geoelectricity are similar! On may 1752, 10, Jean Francois D'Alibard Bard erected a 40-foot-high metal pole on the isolation platform of Mali Garden18km outside Paris, and the end of the pole was pointed. The storm soon enveloped here. According to Franklin's description, a person was carefully placed next to a telephone pole.

The experimental results made Franklin a hero: electricity was obtained from the cloud, stored in a big bottle made of glass and metal (called Leiden bottle), and then used as universal electricity in various experiments, which once again confirmed Franklin's genius!

1in the summer of 952, Franklin didn't know that his experiment had won a great victory in Europe. He tried to erect a metal pole on the towering spire of Philadelphia Christian Church. He was bent on thinking that in order to draw out lightning, the metal pole must rise to a fairly high height, but the structure of the church steeple was too low. Franklin suddenly had an idea, that is, a kite with an iron core.

Franklin propped up a large piece of satin cloth with a cross made of two sticks. This is Franklin's legendary fairy kite! Tie a thin wire at the top of the kite and a metal key at the end of the wire. Franklin manipulated the kite and tied it with a secret insulator-ribbon; When the storm came, the experimenter and his son walked into an empty place and set up a temporary shelter. After the kite rose for quite some time, a thunderstorm cloud gradually approached. The following is Priestley's account:

This cloud seems to have signs of lightning, but it passed without 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 erection, like being ordered, one after another! He was shocked by this scene and quickly reached out and aimed at the key of the online kite. This pioneering work was finally completed, and Franklin finally realized the real lightning.

Franklin continued to draw sparks from the sky and keep them in a Leiden bottle, but one thing must be emphasized here: lightning did not hit the kite. In fact, this is not Franklin's original intention. Franklin originally wanted to use wire conduction to charge the cloud. When there is enough electricity, he reaches out and lets electrons pass through his body to the ground. Fortunately, Franklin escaped. If lightning really hits the kite, he may not be able to sign the declaration of independence or write poor Richard's almanac.

Franklin's report on the above experiment was published in Pennsylvania Journal175210June19. In the same article, he mentioned an article "How to protect the place where you live from lightning", which was later published in Richard's Yearbook of 1753. Franklin believed in the efficacy of lightning rods. He began to strongly recommend the lightning rod at 175 1. Later, the success of the experiment aroused his great confidence in the lightning rod: he was convinced that it could effectively guide lightning and protect people's lives and property.

The purpose of this needle is not only to attract lightning, but also to stop it before it happens. This needle can continuously absorb the amount of lightning in the sky, and before it is strong enough to form lightning, it will introduce conductance to the ground, as Franklin described: "When the electricity between clouds accumulates and releases, the lightning fire will quietly go out."

The significance of this isolation pavilion and kite experiment is not only a pioneering work in electronic history, but also very important to American history. The lightning rod invented in this experiment saved countless lives later.

Revelation: Nature is ever-changing, and no theory or principle can be isolated and absolute. Of course, people's understanding of lightning is not comprehensive, and the research of lightning rod has attracted great attention of scientists all over the world. With the development of scientific theory and technology, lightning protection technology will continue to innovate and improve. The invention of lightning rod seems to be an accident. A coincidence made a great man have a whim and produced an invention. Legend has it that because an apple fell under the tree.

Newton's cool head led to the discovery of gravity. In fact, they are all inevitable accidents. Because these great scientists and inventors have a solid theoretical foundation, their discoveries and inventions are only the concrete crystallization of the flexible application of their theories.