Edison began to experiment with more than 1600 materials as filament materials, and used carbon strips, platinum wires, ruthenium, chromium and other metals as filaments, all of which ended in failure. Edison didn't flinch in the face of failure and some people's cynicism.

After 13 months' efforts, Edison tried more than 6,000 kinds of materials and more than 7,000 times. Finally, he found that cotton thread could be used as a filament and burned it for 45 hours.

Second, Lu Ban invented the umbrella.

When Lu Ban and his sister were playing in the West Lake, it rained and they couldn't enjoy the scenery. His inspiration comes from the lotus leaf on the child's head playing in the rain. After repeated experiments, he finally made an umbrella that can be opened and closed.

Third, Lu Ban invented Mo Dou.

Lu Ban created a carpenter's Mo Dou for marking, which was the result of his inspiration when he saw his mother cutting clothes with powder bags.

When Mo Dou just finished playing, Lu Ban asked his mother for help every time he played the line, holding one end of the chalk line. Sometimes, when mom is making clothes or cooking, she has to put it down to help.

One day, Lu Ban's mother said to him, "Why don't you make a small spoon and hold the chalk line instead of me?" Hearing this, Lu Ban was right! He quickly made one. From then on, one can play with chalk lines. Until now, carpenters have called this small hook "plank wood".

Bell invented the telephone.

On one occasion, Bell tried to send several messages at the same time through a telegraph line. His idea was supported by his wife Mabel Hubbard and his father-in-law.

He first tried to make a "harmony telegram" by connecting two harp-like sets of charged reeds on a wire. At the other end of the wire, each reed has a counterpart with the same frequency. Bell hung two "harps" on a magnetic film. This film is a device that imitates the human ear.

One day, thomas watson, Bell's assistant, fiddled with the caught reed, but Bell heard the plucking sound from the wire in the next room. He recorded the facts and guided further experiments. He is an open-minded and studious person. When he asked others for advice, he got the guidance and help of some famous scientists. The initial telephone call opened a new page in the history of communication.

5. Lu Ban invented the saw.

Once, Lu Ban led everyone to build a palace, which needed a lot of big wood, so he sent his disciples up the mountain to cut down trees. At that time, there were no saws, and all the trees were cut with axes, so few trees could be cut in one day. Luban was in a hurry, so he went up the mountain to see it himself.

The mountain was steep, and Lu Ban grabbed the roots and weeds and climbed up step by step. Suddenly, his finger was cut by grass and he was bleeding.

How can a grass be so powerful? When Lu Ban looked carefully, he found that there were many small teeth on the leaves of grass. He tried it on his finger and it was a cut when he pulled it. This reminded Lu Ban of something. He thought: If you hit a toothed tool with iron and pull it back and forth on the tree, wouldn't it be much faster than cutting it with an axe?

Lu Ban immediately went back to fight and took it to the mountain to try. It was really quick and labor-saving, so Lu Ban invented the saw.