Electrostatic generator, after Van Marum

This is a forerunner of one of the greatest attractions of Teylers Museum: the large electrostatic generator of Martinus van Marum from 1784. In such an instrument, static electricity is generated by friction. Even during his studies in Groningen, Van Marum occupied himself with this subject. In 1774 he designed this electrostatic generator, in cooperation with the instrument maker Gerhard Kuyper. Two innovations distinguished this version from the older ones: A disc of shellac replaced the disc of glass to make the apparatus less sensitive to moisture from the air. Secondly, friction was caused by rotating the disc in a basin with mercury, instead of rubbing it with leather. In actual practice, both ‘improvements’ proved not to be successful. Eventually, not many machines were made.