The English early discovered that a pendulum approximately 39.5 inches long could —for the first time in history — beat accurate seconds, greatly expanding the possibilities of a clock for astronomical observations. Long pendulum clocks at first were hung on the wall with the pendulum swinging freely which affected reliable performance. A "long case" was invented to protect the pendulum. Hence, we call them -Iongcase clocks." Not "grandfather clocks," which was a poem in the 19th century.