Before revision: Io as a tool: 1610–1809 Dutch Orrery of the Jovian system, built circa 1750, used by Harvard professor John Winthrop| alt=A brass, clock-like mechanical device in a museum display case, with a small card with the number 8 printed on it.
After revision: Io as a tool: 1610–1809 alt=A brass, clock-like mechanical device in a museum display case, with a small card with the number 8 printed on it.