English: Gold-leaf electroscope from "Opfindelsernes Bog" (Book of inventions) 1878 by André Lütken, Ill. 284. This is an antique scientific instrument that detects electric charge consisting of two delicate gold leaves suspended from a metal electrode. It is demonstrating electrostatic induction. When a negatively charged object is brought near the top terminal, the charges in the vertical conductor separate. The positive charges are attracted to the top of the terminal, while the negative charges are repelled into the gold leaves. Since they have the same charge, they spread apart from mutual repulsion. The two grounded strips in the jar flanking the leaves are a safety measure; if too strong a charge is applied to the instrument, the leaves will touch the ground electrodes and discharge before they tear.