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.
Thomas Edison & The History of Electricity. 1876 was also the year that Thomas Alva Edison opened a laboratory in Menlo Park, New Jersey, where he could explore the possibilities of the dynamo and other electrical devices that he had seen in the Exposition.