Complex sentence: A primitive form of frictional electrical machine was constructed around 1663 by Otto von Guericke, using a rotating sulphur globe rubbed by hand, although it may not actually have been rotated during use.
Split into simpler sentences: A primitive form of frictional electrical machine was constructed around 1663 by Otto von Guericke, using a sulphur globe that could be rotated and rubbed by hand. It may not actually have been rotated during use.