Decline
Verge escapements were used in virtually all clocks and watches for 400 years. Then the increase in accuracy due to the introduction of the pendulum and balance spring in the mid 17th century focused attention on error caused by the escapement. By the 1820s, the verge was superseded by better escapements, though many examples of mid 19th century verge watches exist, as they were much cheaper by this time.
In pocketwatches, besides its inaccuracy, the vertical orientation of the crown wheel and the need for a bulky fusee made the verge movement unfashionably thick. French watchmakers adopted the thinner cylinder escapement, invented in 1695. In England, high end watches went to the duplex escapement, developed in 1782, but inexpensive verge fusee watches continued to be produced until the mid 19th century, when the lever escapement took over. These later verge watches were colloquially called 'turnips' because of their bulky build.
The verge was only used briefly in pendulum clocks before it was replaced by the anchor escapement, invented around 1660 and widely used beginning in 1680. The problem with the verge was that it required the pendulum to swing in a wide arc of 80° to 100°. Christiaan Huygens in 1674 showed that a pendulum swinging in a wide arc is an inaccurate timekeeper, because its period of swing is sensitive to small changes in the drive force provided by the clock mechanism.
Although the verge is not known for accuracy, it is capable of it. The first successful marine chronometers, H4 and H5, made by John Harrison in 1759 and 1770, used verge escapements with diamond pallets. In trials they were accurate to within a fifth of a second per day.
Today the verge is seen only in antique or antique-replica timepieces. Many original bracket clocks have their Victorian-era anchor escapement conversions undone and the original style of verge escapement restored. Clockmakers call this a verge reconversion.
Read more about this topic: Verge Escapement
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