The Astronomical Clock

Remember in the 1970’s when wristwatches were selling with date windows?

It was the new trend and the modern mass produced wristwatch industry has not looked back. Of course if the average consumer knew their clock history, they would have been disappointed, as then they would certainly have known it could be capable of so much more.

Surely the need to tell time - control the day, and the simple mechanisms utilizing the movement of the sun or the burning of a candle, the movement of sand or water and the intellectual curiosity about the sun, moon and stars collided in a serendipitous moment of a horologist – a scientist staring off into space. The phrase my “wheels are turning” to indicate a thinking process must have derived from the science of horology. Just imagine the early horologists dreaming of connected arbors, pinions, gears, and wheels, with a few springs and clicks thrown in, all at various ratios, connecting to more dials telling more wonderful things, all related to the sun, moon stars and the passage of time. Why stop at telling the time when with a few (well perhaps more than a few), more wheels and dials we can tell so much more. This is the point where the Astronomical clock comes in. Some say the indication of time was secondary to all the wonderful things that could be accomplished once the science and math was understood behind the dial.

The design of the astronomical clock is considered to have been influenced by the design of the astrolabe and the early Greek Antikythera mechanism. The astrolabe was first invented in 150 B.C. in ancient Greece and is a complex inclinometer used to determine the positions of the Sun, Moon, planets and stars. The Antikythera mechanism is an ancient analog computer that was created in approximately 100 B.C. to calculate astronomical positions. The astronomical clock appeared as early as 1020-1101 in China, 1206 in the Mid-East, 1336 in England and 1348-1364 in Italy. These clocks are actually among the earliest examples of a mechanical weight driven movement and are a chronological step up from the early water driven geared movements. A few famous examples of Astronomical clocks from the earlier history of the mechanism are still visible today inside or on the outside of public buildings located throughout Europe.

We are fortunate here at the Horologist of London to own a rare example of an astronomical dial longcase clock by William Dutton of London c 1775. This wonderful example of the science of horology stands tall on a mahogany ionic column. The painted dial has various windows through which pass the astrological symbol for the time of the year, a tidal indicator that shows high or low tide at London Bridge on the Thames river, the day of the week, the date of the month, the number of days in the month, the time of sunrise, the length of twilight, the phase and age of the moon, and… a few more details. Stop by the shop to view an example of this break through moment in horology.

A date window… 900 years later, pretty funny.

Astrolabe