English: Gilbert's "versorium", the first crude electroscope, invented by English physician William Gilbert around 1600. This was the first electrical measuring instrument. It consisted of a metal needle free to turn on a pivot, similar to a compass needle but unmagnetized. When an object charged with static electricity was brought near, the needle would swing around and point to it. The motion was due to the attraction of a temporary charge of opposite polarity induced in the near end of the needle by the external charge.