The Venerable Bede (673?-735), a monk, wrote the "Ecclesiastical" History of the English Nation" a monumental account of his time. In this book are described the properties of the jet as those of amber. Also the jet, if rubbed, attracts bits of feather.
If not only the amber has this property, could be possible the existance of other unknown causes.
Was William Gilbert, physician to Queen Elizabeth I, to make the next important discovery. His book "De Magnete" (About Magnets) was published in 1600. It gave proof that the attraction created by rubbing was not magnetic.
He called it "electric", from the greek "electron" meaning "amber".
This word was successful !

Gilbert is famous for his studies on magnetism. (figure above)
He noticed that is not possible to divide a lodestone in two parts: cutting a lodestone in two parts we have two lodestone and not two half.

Gilbert was the first man to assume that the earth is a big magnet and the magnetic needle was attracted by the terrestrial magnetism. (fig. below).
Before him was general belief that the magnetic needle was drawn by celestial forces.
Gilbert thinked that was possible to measure the latitude by the compass.