This experiment is devised by the Leiden professor Willem Jacob s Gravesande. It shows the expansion of solid substances by heat. Normally, the ball fits exactly through the ring. However, when the ball is heated, it remains lying on the ring, because the ball expands and becomes larger because of the heat. The moment the temperature of the ball gets lower again, the ball will fall through. This is one of the many demonstration instruments devised by the Leiden professor Willem Jacob s Gravesande in order to illustrate physics teaching.
's Gravesande's ring & ball
1750 - 1774