Christiaan Huygen patented the pendulum clock and escapement in 1657.
The Connecticut clock companies made them affordable in the early 19th century.
Shorten the drop and the clock runs faster.
Repeat as necessary until the clock keeps time.
Some clocks, notably French regulators, will have both adjustment systems.
Some French pendulum bobs have two or three glass vials filled with mercury or steel rods to imitate such.
One end of this rocker mechanism has a locking face the other end has an impulse face.
This tick-tock is called the beat and should be perfectly even.
If the clock goes tick-TOCK or TICK-tock, it is out of beat and wont keep proper time.
The simplest method is to shim the feet on one side of the clock until the beat is even.
Another method is to adjust the anchor mechanism regardless of its style in relation to the pendulum rod.
This rocker is connected to a wire or a rod or linkage that terminates at the pendulum rod.
Again, personal experimentation is required.
A clock should only require adjustment when moved to a new location or after professional cleaning and oiling.
