1840Indian rebirth

Convenient circulation is indeed one of the reasons. Compared with gold coins, silver coins and copper coins are undoubtedly more suitable for use in daily life.

But this is not the main reason. The reason why Mashao needs more silver coins is mainly to realize an invention.

After Chavez left, Ma Shao first found a few bottles of nitric acid to briefly purify the silver in the silver coins. After all, the silver content of these Spanish silver coins was not high, only about 90%.

Then he gave the purified silver to a blacksmith and ordered him to make the silver blocks into silver wire.

After getting these silver wires, Ma Shao can officially start his invention - the metal detector.

Strictly speaking, he has invented the metal detector. After all, the principle of this thing is not complicated. It is mainly an eddy current effect and it is still the content of high school physics. Of course he can make it.

But the problem is that the performance of the metal detector he invented before was really poor. At the beginning, it could only respond if metal was attached to it.

Maybe the design is not good enough, or maybe his craftsmanship is not good enough.

Of course, it's more likely that the front-end technology is a bit inadequate. The battery is an improved voltaic pile, and the voltage is not stable enough. The indicating device is a small fan, which is not very intuitive.

All in all, no matter how he improved it, the performance of the metal detector was still not ideal. So in the end he planned to replace all the wires with silver wires to see if he could improve it.

After all, silver is the most conductive metal. Although it is not much better than copper, it is still worth a try.

Soon, he will go to California to search for gold mines. A metal detector, even the simplest one, is much more efficient than using the naked eye.

Ma Shao replaced all the conductive parts in the metal detector with silver and then re-experimented.

This detector is so simple and a bit bulky. First of all, it is a square wooden box containing a voltaic pile.

There is an opening in the wooden box, and wires wrapped in cowhide protrude from it, and are finally connected to the coil and indicating fan.

Of course, the coil and handle are also partially protected by a wooden shell, and a glass cup is attached to the indicator fan to prevent them from being affected by the flow of outside air.

For ordinary people, the wooden box containing the battery may need to be carried on the back, but with the size of a horse whistle, it is enough to carry it in the hand.

In the chief's hall, there are some gold coins on the ground.

Ma Shao held the battery box in one hand and the handle in the other, slowly approaching the gold coins from a distance while observing the changes in the fan.

Under his careful debugging, the fan speed is relatively stable, at least according to the naked eye.

As the metal detector and gold coins get closer, the induced magnetic field generated by the gold coins changes the current in it, and the rotation of the fan also changes accordingly. It slows down at first, and when the whistle retracts the detector slightly, the fan speed becomes faster again.

When the metal is far away and sometimes close, the fan jumps repeatedly between fast and slow.

The accuracy is pretty good, but the detection range is still not far and it can only detect metal in front of you.

It seems like this is the only way.

At this time, I came in from the outside on a rainy day, and immediately saw the thing in the horse whistle's hand, and asked: "What is this?"

"Metal detector." Ma Shao said, placing the wooden box on the table and passing the handle, "Do you want to try it?"

Rainy Day took the handle curiously: "How do I use it?"

"Put this close to the place you want to detect. If there is metal there, the fan speed will tell you." The whistle pointed to the detector's coil.

"Really or not?" Rainy Day was surprised. As he spoke, he couldn't wait to pick up the detector and approach the gold coins next to him.

Sure enough, as Ma Shao said, as soon as the detector got close to the gold coin, the fan on it immediately started to slow down.

Around the gold coin, every change in distance will bring about a change in the fan speed, and once it is away from the gold coin, the fan returns to stability.

"This...incredible!" I couldn't help but open my eyes on the rainy day, and then tried it with copper and iron, and found that copper and iron can also be detected by the detector.

"How did you do it?" He turned the detector over and looked at the silver wire coil that was not wrapped in a wooden shell.

"You should be able to imagine that I talked about some of its principles in the mathematics and physics training class." Ma Shao said with a smile.

Rainy Day scratched his head. Obviously he was not very good at mathematics and physics: "Is it Faraday's...law of electromagnetic induction?"

"Absolutely." Ma Shao nodded, "Specifically, this detector uses an effect I call 'vortex'. Of course, others may not be fully aware of this effect."

"Including Faraday," he added.

Faraday is still alive and is a scientist with a high reputation.

"Sounds very powerful." Rainy Day touched his chin, "But this thing doesn't seem to have much practical significance. What do you plan to use it to detect, iron ore?"

Ma Shao: "It can't detect iron ore. In fact, it can't detect almost any mine. After all, it is a metal detector, not a metal mineral detector - except for gold mines."

"Why?"

Ma Shao continued to explain: "Because gold often exists as a simple substance in nature."

Rainy Day thought for a while: "So you plan to use it to find gold mines?"

"Hmm... not really." Ma Shao thought for a moment, "After all, gold mines are always very rare. In a place as big as North America, how long will it take this little detector to find gold mines."

He actually wanted to detect gold mines.

He believes that although the performance of this detector is not very good, it is at least better than the naked eye.

The detection area is not too big. It should be relatively easy to detect results near Sacramento.

But it is obviously not appropriate to say it directly now, after all, it is so early... He said that there is a gold mine near Sacramento, which will inevitably give people a feeling of official approval.

And if you don't specify to go to Sacramento to find gold mines, from a common sense point of view, it is too stupid to use this thing to find gold mines all over the world. You can't do this kind of thing if you have cerebral thrombosis in ten years.

"In that case, what's the use of this thing?" Rainy Day asked again.