Dead-beat escapement

By the late 17th century, an English watchmaker by the name of Thompson had devised the dead-beat escapement. He even made a copy of one which he offered to the Grand Dauphin. The item quickly proved unusable and was relegated to a showcase in Versailles, among other curiosities. His pupil Graham took over from his master's work and perfected his invention by using a lever, a small part shaped like a ship's anchor, whose oscillating motion, by engaging with a toothed wheel, locked as it went to and fro. Unfortunately, although the device produced excellent results on vertical regulators and fixed pendulums, its application was not transferable to flat-cased portable watches.