Apart from Newton's doubts about apples, who discovered or invented anything because of doubts?

Watt was born in Greenock, England. Because his family is poor, he has no chance to go to school. He first worked as an apprentice in a watch shop, and then as an instrument repairman at Glasgow University. Watt is clever and studious. He often takes time to listen to professors' lectures. Plus, he plays with those musical instruments all day, and he has a lot of knowledge.

1764, Glasgow University received a newcomen steam engine to be repaired, and the task was given to Watt. After Watt repaired it, I watched how hard he worked, just like an old man panting and walking with a heavy load, and felt that it should be improved.

He noticed that the main problem was that the cylinder body was hot and cold with the steam every time, which wasted a lot of heat. Can you keep the temperature low and the piston work as usual? So he rented a cellar at his own expense, collected several scrapped steam engines and decided to build a new machine.

From then on, Watt fiddled with these machines all day, and after two years, he finally took on a new look. But when trying to light the fire, the tank leaked everywhere. Watt tried to wrap it in felt and tarpaulin. Months passed, but he still failed to solve the problem.

One day, he squatted in front of the cylinder to observe the cause of air leakage. He accidentally rushed out with hot air. He hurriedly dodged, and his right shoulder was red and swollen, as if he had been cut by a hot knife, which made him feel terrible. He's really depressed. At this time, it was his wife who gave him courage, and her spur aroused her ambition to continue her research.

He went back to the underground laboratory, browsed the past data again, pulled himself together and went on working. Tired, I always let the stove boil a pot of water and drink tea. One day, while drinking tea, he looked at the moving lid of the pot. He looked at the pot on the stove and the cup in his hand, and suddenly he was inspired: the tea is getting cold, so pour it into the cup; If the steam is cold, why not pour it out of the cylinder?

Taking this into account, Watt immediately designed a condenser separated from the cylinder, which increased the thermal efficiency by three times, while using only one quarter of the original coal. As soon as this key place broke through, Watt suddenly felt that the future was bright. He went to the university to ask Professor Black some theoretical questions, and the professor introduced him to Wilkin, the technician who invented the boring machine. Technicians immediately made the cylinder and piston by boring the barrel, which solved the most troublesome air leakage problem.

1784, Watt's steam engine was equipped with a crankshaft and a flywheel. The piston can be continuously driven by steam coming from both sides, and the valve does not need manual adjustment, so the world's first real steam engine was born.

David

David was a famous prodigal son when he was a child. Clever as he is, he just doesn't want to learn. When he was at school, he always had a hook and fishing line in one pocket and a slingshot in the other. Before going to school, he always goes to the river to shoot birds and catch fish.

After my father died, my mother couldn't live with her five children, so she had to send David to a pharmacy as an apprentice. By the end of the month, others got their salaries, but David didn't get his share. David reached out to the boss for money, but the boss gave David a hard blow in front of everyone and said, "How dare you reach out and ask for money?" The master and apprentice in the shop burst into laughter.

Where has David been so humiliated? From then on, he made up his mind to return to the prodigal son and study hard. He used the conditions of pharmacy to study chemistry. At this time, Professor Bedoz set up a gas sanatorium, and David was invited to work together. Here, David found a kind of "laughing gas", and David became famous.

1803, David was elected as a member of the Royal Society. He knows that opportunities are rare, so he studies harder. Among many research topics, David is particularly interested in the electrolysis of voltaic cells. He thinks that electric energy can decompose water into hydrogen and oxygen, so it must also decompose other substances into new elements. Caustic alkali is commonly used in chemistry. Try it.

So he made a piece of caustic soda into an aqueous solution and then electrified it. The solution immediately boiled and heated, and bubbles appeared near the two wires. David thought that the caustic soda was decomposed at first, but later he found that the gases coming out were hydrogen and oxygen, which means that only water was decomposed, and the caustic soda didn't move at all.

David's stubbornness is about to appear. If water attack doesn't work, then fire attack. This time, after he melted the caustic soda, he turned on the power. Hey! There is a small flame in the place where the conductor contacts with caustic soda, which is lavender. This made David very happy, but he soon became worried again. How to collect this substance? The melt temperature is too high and flammable. It will catch fire when it decomposes. It seems that fire attack is not a good idea either.

165438+1October 19 is the annual Bekkerel lecture day of the Royal Society. David is full of hope that this time he can bring a newly discovered element. But the reporting date is coming, and there is still no clue of electrolytic caustic soda. He thought hard for more than ten days, and suddenly came up with a good idea that day: slightly wet the caustic soda to make it just conductive and contain no residual water.

Wet caustic soda is simple. As long as it is left in the air for a while, it will automatically absorb water and form a wet layer on the surface. David really succeeded this time. He electrolyzes metallic potassium.

Bushnell invented the submarine.

1775, the North American War of Independence finally broke out. Under the leadership of Commander-in-Chief Washington, the American people took up arms one after another and launched a life-and-death battle with the British army, driving the British army from the mainland to the sea. The whole country celebrated this decisive victory. How can we tolerate the glory of other countries in destroying Britain and then organize the defeated troops to make a comeback? Although the British colonial rulers lost their land superiority, their maritime superiority still existed. They assembled a large number of warships and bombed the US coastal defense forces in turn, causing heavy casualties and greatly weakening the momentum of the US military. The British army became more and more rampant when it saw that the American army had neither the potential to parry nor the strength to fight back. Warships are on the rampage along the coast, throwing their weight around. He fired several shots at the coastal defenders from time to time, and then swaggered away triumphantly. Faced with the provocation and bullying of the British army, the American soldiers gnashed their teeth with anger: "This is simply riding on someone's neck to shit! If I can sneak past and sink some of its ships, I should feel even more revenge! "

One of the soldiers, David bushnell, didn't swear, but kept his mouth shut and said nothing. He thinks it's no use shouting. We should work out a way to deal with enemy ships as soon as possible. Bushnell has been thinking hard about how he can bypass their boat at once. From the air? No, it is easy to expose the target; From underwater? No, who can resist swimming for so long? Besides, there is not enough strength! What should I do? "He's knocking.

One night, after he and several soldiers were fired, he went for a walk by the sea. They climbed to the rocks; While chatting, enjoy the sea view in the sunset. I have seen enough of the distant view and close view, the water is clear and the aquatic life is vivid. They saw a group of lively small fish swimming freely in the water, as if they were foraging for food and playing. Suddenly, a big fish swam quietly under the water, swam under the small fish, jumped up suddenly and bit a small fish. The other little fish were so scared that they parted ways. The soldiers saw this "naval battle" in the underwater world and found it very interesting. Bushnell was greatly inspired by this: this is how the clumsy big fish caught the clever and quick small fish. Can you build a ship like a big fish, and dive into the bottom of a British warship in the latent water unnoticed, and lay a mine to blow it up and sink it? If you can do it, how happy it will be! The more he thought about it, the more fascinated he became. He didn't sit there until his companion told him to go. "Ah! What's the matter with you? I miss your lover, hehe! " His companion slapped him.

"I have an idea, I can sink!" Bushnell's words puzzled his companions. So he elaborated his thoughts. Hearing this, the companions all thought it was a good idea. Suddenly someone asked, "Fish can float and sink freely in the water, but a boat is different. It's easy to float on the water, but can you dive? " Bushnell was asked to remain silent. Yes, how can we make the ship float and sink? Why can fish do this? He patted his thigh: "I have! This kind of fish floats to the surface for a while and dives to the bottom for a while, relying on the swim bladder in its belly. If we also forge a' prostitute' for the ship, won't the problem be solved? "

Bushnell led his companions to build a secret ship that can sneak underwater. I wanted to make it look like a fish, but it looked like a turtle. Therefore, the companions gave it a code name-tortoise. This secret spaceship, code-named "Turtle", has a water tank similar to a swim bladder at the bottom, and there are two pumps in the water tank. When the ship sinks on the water, it will fill the water tank with water. When the ship is going to float underwater, it will drain the water in the cabin and press the air into the water tank. Imitating the fin of a fish, two propellers were installed outside the turtle: one for forward and backward, and the other for upward and downward. In addition, the turtle has a rudder at the tail, which can control the course.

One night, bushnell, with a few soldiers, drove the "turtle" quietly close to the British warship, then dived into the water and dived under the British warship. They want to use the drill pipe at the top of the turtle to drill through the enemy ship and then release the mine. Unexpectedly, the bottom of the British ship was covered with a thick layer of metal and could not be drilled in for more than an hour. The soldiers couldn't hold their breath down there, so they had to come up for air. At this time, the night is deep and dark, and the water and sky are the same, and I can't tell the direction at all. The British army found the "turtle" and started warships to pursue it. The "turtle" was scared to retreat again and again, but it could not get up quickly, and it was about to be hit by an enemy ship. At this extremely critical moment, bushnell used his quick wits to untie the spare mine, lit the fuse, and hurried into the "Turtle", which dived into the water. The British ship is looking for the whereabouts of the monster. Suddenly, there was a loud noise beside the ship and the warship caught fire. The British army turned around and fled while fighting the fire, for fear that the monster would quietly follow. Since then, British ships have never dared to show off near the American coast.

Later, after people's continuous improvement, they made a new mysterious weapon-submarine. The submarine showed great power in the naval battle. In World War II, only German submarines sank 782 transport ships of the Anglo-American Atlantic Fleet, which caused great damage to the other side's transport lines.

At present, submarines are mainly used for developing marine resources and scientific investigation in addition to combat. Its role has also changed from destruction and interference to benefiting mankind.

The problem of weighing the crown

In the eyes of ordinary people, Archimedes is a "freak". In the words of Plutarch, a Roman historian, "He seems to be an enchanted man. He doesn't care about food or his body." Sometimes, the rice is put on the table and asked to eat, but he doesn't seem to hear it. He is still drawing his geometry in the ashes of the brazier. His wife should look after him at all times. For example, when he rubbed his body with oil, he just sat and oiled himself and forgot what he had done. His wife is more afraid of sending him to the bathhouse to take a bath. The joke was caused by a new crown of the king.

Not long ago, the king asked a craftsman to build him a golden crown. The king gave the craftsman the gold he needed. The craftsman's craft is very clever, and the crown produced is exquisite and unique, and the weight is as heavy as the gold given by the king at the beginning. However, someone reported to the king: "When making the crown, the craftsman swallowed some gold privately and mixed the same weight of silver." Hearing this, the king became suspicious, so he called Archimedes and asked him to try to determine whether the gold crown was mixed with silver and whether the craftsmen kept the gold for themselves. Archimedes was stumped this time. When he got home, he thought hard for a long time and couldn't find a way. I can't eat, sleep or take a shower every day, as if I were possessed.

One day, the king sent someone to urge him to report to the palace. His wife saw that he was too dirty and forced him to take a bath. When he was taking a bath in the bathhouse, he was still thinking about weighing the crown. Suddenly, he noticed that some water overflowed from the side of the bathtub when his body sank into it. At the same time, he felt that the deeper he went into the water, the lighter he was. So, he immediately jumped out of the bathtub, forgot to wear clothes and ran to the street of the crowd. He ran and shouted, "I found it, I found it, and the solution to the crown was found!" " "

After he entered the palace, he said to the king, "Please allow me to do an experiment, and then I can report the result to you." The king agreed. Archimedes put the gold, a piece of silver and the crown, which are as heavy as the crown, in the basin one by one, and saw that the gold nugget discharged less water than the silver nugget, while the crown discharged more water than the gold nugget.

Archimedes said to the king, "The crown is mixed with silver!" " "The king looked at the experiment and didn't understand. Let Archimedes explain. Archimedes said, "One kilogram of iron is bigger than one kilogram of wood. If you put them in water separately, the big wood will discharge more water than the small iron. I apply this principle to gold, silver and crowns. Because the density of gold is high and the density of silver is low, if gold and silver are equally heavy, the volume of silver must be greater than that of gold. Gold nuggets and silver nuggets with the same weight are put into water, and the amount of water discharged by gold nuggets is less than that of silver nuggets. The experiment just now shows that the crown discharges more water than the gold nugget, indicating that the density of the crown is smaller than that of the gold nugget, which proves that the crown is not made of pure gold. " Archimedes' methodical narration persuaded the king. The experimental results prove that the craftsman put the gold in his pocket.

This experiment of Archimedes is the embryonic form of "hydrostatics". However, he did not stop there and continued to study the floating body problem in depth. Results Archimedes principle, an important principle in natural science, was discovered. That is, when an object is immersed in a liquid, the volume of the displaced liquid is equal to the volume in which the object is immersed; Keep the buoyancy of the floating body equal to the weight of the liquid discharged by the floating body.