A Pendulum Clock

A Pendulum Clock is a clock that uses a pendulum as its primary timekeeping element. From its creation in 1656 by Christiaan Huygens until the 1930s, the pendulum clock was the world’s most accurate, which accounts for its common use during that period.

Galileo Galilei discovered the key property that makes pendulums useful timekeeping elements: isochronism, which means that the period of swing of a pendulum is approximately the same for different sized swings.

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Galileo had the idea for a pendulum clock in 1637, and it was partly constructed by his son in 1649, neither lived to see their idea in operation.

The Pendulum Clock, invented in 1656 by Dutch scientist Christiaan Huygens, and patented the following year, was inspired by investigations of pendulums by Galileo Galilei beginning around 1602.

The introduction of the pendulum, the first harmonic oscillator used in timekeeping, increased the accuracy of clocks enormously, from a variation of about 15 minutes per day to just 15 seconds per day, which lead to their rapid widespread use. Pendulum clock soon became a status symbol and an expression of  ‘class.’

For Pendulum Clocks to maintain their purported accuracy, they must be stationary. Any motion or accelerations in the positioning of the clock will affect the motion of the pendulum, thereby causing inaccuracies. Other timekeeping mechanisms must be used in devices that are to be portable. Grandfather Clocks, Pendulum Clocks, are now kept by and large for their decorative and antique value.

These early Pendulum Clocks, due to their verge escapements had wide pendulum swings of up to 100°. Huygens discovered that wide swings made the pendulum inaccurate, causing its phase, and thus the rate of the clock, to vary with inevitable discrepancies in the driving force behind the Pendulum Clock’s accuracy.

[Escapements and their variations will be discussed in future on the ‘Grandfather Clock Terms’ website page.]

The ‘seconds pendulum’ (also called the Royal pendulum) is named such due to each swing duration being one second. Thus, the ‘seconds pendulum’ became widely used. The long narrow clocks built around these pendulums, first made by William Clement around 1680, became known as Grandfather Clocks.

Clockmakers soon came to the realization that pendulums with swings of only a few degrees are isochronous. This motivated the invention of the anchor escapement around 1670. This escapement variation reduced the pendulum’s swing to a mere 4°-6°. The anchor escapement allowed for more accuracy, the clock’s case to accommodate longer, slower pendulums, thus needing less power and decreasing wear on the movement. The increased accuracy resulting from these developments created the development of the minute hand, previously very rare, to be added to clock faces beginning around 1690.

More clarifications and complications to come. Keep Reading; keep learning!

Grandfather Clocks for Home

A Pendulum Clock Article

A Pendulum clock: Part 3