Longcase Clock - Origin

Origin

The advent of the longcase clock is due to the invention of the anchor escapement mechanism by around 1670. Prior to that, pendulum clock movements used an older verge escapement mechanism, which required very wide pendulum swings of about 80-100°. Long pendulums with such wide swings could not be fitted within a case, so most freestanding clocks had short pendulums. The anchor mechanism reduced the pendulum's swing to around 4° to 6°, allowing clockmakers to use longer pendulums, which had slower "beats". These needed less power to keep going, caused less friction and wear in the movement, and were more accurate. Almost all longcase clocks use a seconds pendulum (also called a "Royal" pendulum) meaning that each swing (or half-period) takes one second. These are about a metre (39 inches) long (to the centre of the bob), requiring a long narrow case. The long narrow case actually predated the anchor clock by a few decades, appearing in clocks in 1660 to allow a long drop for the powering weights. However, once the seconds pendulum began to be used, this long weight case proved perfect to house it as well. British clockmaker William Clement, who disputed credit for the anchor escapement with Robert Hook, produced the first longcase clocks around 1680. Within the year Thomas Tompion, the most prominent British clockmaker, was making them too.

Modern longcase clocks use a more accurate variation of the anchor escapement called the deadbeat escapement.