This electrostatic generator is capable, under dry atmospheric conditions, of producing sparks up to 80mm long. The revolving discs are 300mm in diameter. The neutralising bars are provided with replaceable tinsel tapes. The charge collectors are carried on a horizontal insulating beam and also have replaceable tinsel pick-ups. A pair of leyden jars are incorporated. The apparatus is mounted on a plastic surfaced baseboard with rubber feet, which also carries a pair of earthing terminals for the Leyden jars.