There are two inner workings of the grandfather clock that I would like to discuss today, the pendulum and the escapement mechanisms. These are an integral part of the functionality of the clocks and activate the beautiful bells that we hear in our homes.
As I have discussed in another article, some of the earlier long case watches had a 100 degree pendulum arc. Long pendulums with such wide oscillations were found in large open clocks, usually on the outside. With the invention and use of the escapement mechanism of the anchor, the pendulum clock was able to reduce the oscillation radius of the pendulum from 4 to 6 degrees. The introduction of the long case or grandfather clock is due to the invention of the escapement mechanism of the anchor.
(An escapement is the mechanism in a mechanical clock that maintains the pendulum swing and advances the clock wheels with each swing. An anchor escapement is a type of escapement used in pendulum clocks).
Most of these clocks had short pendulums to be contained within a box. As advancements were made in escapement mechanisms, watchmakers were able to use longer pendulums, which had slower “beats” but kept the radius of oscillation shorter. They needed less energy to keep going. They had less friction and wear on the move and were more accurate.
Modern grandfather clocks use a more precise variation of the anchor escapement called a dead beat escapement. The inactive form of the anchor escapement was initially used only in precision clocks, but due to its superior precision, its use spread during the 19th century to most quality pendulum clocks. Most pendulum clocks manufactured today use it. Most of the height of a long-case watch is used to hold the long pendulum, the weights, and the two chains attached to the weights.
Traditionally, long case watches were made with one of two types of movements, the eight-day movements and the one-day (30-hour) movements. Eight-day clocks are often driven by two weights, one driving the pendulum and the other the striking mechanism. These movements usually have two locks on each side of the dial or watch face to wind each one.
In contrast, 30-hour clocks often had a single weight to power both the timing and the striking mechanisms. Some older 30-hour clocks were made with fake locks on the watch face. This was for customers who “wished” their home guests to think that the home could afford the most expensive eight-day clock. Cable watches are wound by inserting a special crank (called a “key”) into the holes in the watch face and turning it. The lack of winding holes in the face or face of the watch shows that it is a 30 hour watch.
Other long-case watches are chain-operated and have weights suspended by chains that wrap gears in the watch mechanism. To wind a chain-driven grandfather clock, the end of each chain is pulled down by lifting the weights.
Today we also have 31 day and quartz movements on some long case or grandfather clocks.
At the beginning of the 20th century, quarter-hour chime sequences were added to long case watches.
Most long-case clocks use the seconds pendulum (“Real” pendulum). These are approximately 39 inches long. A second pendulum takes 2 seconds to make the full swing. In 1670, William Clement used the seconds pendulum in his improved version of Christian Huygens’ original pendulum clock.
Christian Huygens was credited with inventing the original pendulum clock. He was also known as an astronomer, physicist, and watchmaker (watchmaking is the art and science of time). He was also an early science fiction writer. His work included many areas of study, including research and inventions related to timekeeping and the pendulum clock. He was a fascinating man.
(An interesting tidbit is that in Britain around 1855, the British ‘yard’ was defined as a specific fraction of the pendulum’s length of seconds.)
