A correlation is a single numerical value that is used to describe the relationship between two variables. All correlations have strength and direction. When two variables have a positive correlation, that means the two variables move in the same direction. The closer a positive correlation is to 1, the stronger it is.
William Gilbert discovered electricity, not Nikola Tesla. Nikola Tesla invented things. not discovered electricity. Again, William Gilbert discovered it and named it. He did this in the 1600s. It wasn't Nikola Tesla.
But further research on electromagnetism and any practical use of electricity would require a source of continuous current, which was not available until 1800, when Alessandro Volta invented the first electric pile, the forerunner of the modern battery. Alessandro Volta was born in Como, Italy in 1745, to a wealthy noble family. He attended the Como Jesuit school and a local seminary. His teachers tried to persuade him to enter the priesthood, while his family wanted him to study law. But Volta, even at age 14, knew his real interest was physics.