Anchor escapement clocks with 1 meter (39 inch) seconds pendulums that came to be called longcase or 'grandfather' clocks. The anchor increased the accuracy of clocks so much that around 1680–1690 the use of the minute hand, formerly the exception in clocks, became the rule. The anchor escapement replaced the verge in pendulum clocks within about fifty years, although French clockmakers continued to use verges until about 1800. Many verge clocks were rebuilt with anchors. In the 18th century the more accurate deadbeat form of the escapement replaced the anchor in precision regulators, but the anchor remained the workhorse in home pendulum
Escapement patented it in 1782. The early forms had two escape wheels. The duplex escapement was difficult to make but achieved much higher accuracy than the cylinder escapement, and could equal that of the (early) lever escapement and when carefully made was almost as good as a detent escapement. It was used in quality English pocketwatches from about 1790 to 1860, In the duplex, as in the chronometer escapement to which it has similarities, the balance wheel only receives an impulse during one of the two swings in its cycle. The escape wheel has two sets of teeth (hence the name