This rugged, sensitive electroscope can accept various accessories to change its capacitance. A sensitive aluminium vane is balanced in a vertical position on a metal support which is insulated from its base. The vane is easily observed and projected on a chalkboard (Light Source, not included) on which an arbitrary scale has been marked. Height without attachments is about 9". Four attachments, each equipped with a banana plug which fits the vane system top, are included : a 1" conducting sphere; a 3" conducting sphere; a proof plane with detachable insulating handle and an aluminium cup (Faraday ice pail). Attachments can be charged using either our Electrophorus or our Power Supply (not included). With instructions.