 by just using a prominent magnet. So they had this chariot where at the end of the chariot small grid of this thing. So it used to look like this. So it used to look like this. And the person done like this. So they start moving like this. So now the person is moving where your enemy might not be able to move properly the food that they just enjoyed at that time. This emperor used to attack them during that time because he has a navigation device. So he used to navigate his army properly in his fort like that. And also not just during land force in the sea, you might have seen the movie Titanic. So that ship already knew that they are going to go right to the ice bar. So you have to be moving, very very quick moving with him. Have you also moved in 300? So they are moving together. A great discovery of this. This was the only application of magnets for hundreds and hundreds of years. It always gets aligned in a particular direction because huge magnet and magnet are in a different direction. But later on they realized that there is nothing like that inside the earth. The magnetism of earth. I got that. But then that they understood that. And he came, he got the answer. You can generate because if you know how to. You can study magnetism. Then you will study as a charge. Like the way the electrostatics works. In the electrostom, then the electric field due to a single charge. Then the electric field due to a line of charge.