The large electrostatic generator (Van Marum electriseermachine) is a large handcrafted electromechanical instrument designed by Martin van Marum and built by John Cuthbertson in 1784 for the Teylers Museum in Haarlem, where it forms the centerpiece of the instrument room. The concept of an electrostatic generator was new, and the battery (array) of leyden jars was the largest ever built (only one of the 4 sets of leyden jars is on display to conserve space). The two glass disks of the generator are 1.65 meters in diameter, and the machine is capable of generating a potential of 330,000 volts. No photographer credited, undated.