Let's Talk Clocks

What constitutes a "clock"? The Latin horologium could refer to a clock or a timepiece of a sundial or the building or structure designed to support any of those.

Modern horology, the study of the measurement of time, distinguishes clocks which mark time by striking something (the word "clock" comes from French cloche, "bell"), whereas a timepiece does not. So a timepiece can mean a watch, a sundial, a clepsydra, or an hourglass, etc.

The sundial was likely the earliest way to measure time: a shadow on a flat surface displays the progression of the sun.

The clepsydra (Greek κλεψύδρα, literally "water thief"), was used in Babylonb, Persia, and Egypt as far back as the 16th century BCE. The simplest form is a bowl or other vessel with a hole from which the water drains, and markings to match drainage levels with the passage of time. The Greco-Roman world devised an in-flow (rather than out-flow) method which, as water filled a container, would trigger a sound, creating an "alarm clock." Water clocks evolved that used gears and escapement mechanisms to produce greater accuracy.

An escapement is a gear mechanism that ticks forward and back to cause another piece to advance. The illustration shows how this works in a pendulum clock, advancing the hands. The use of the escapement was crucial to the development of mechanical clocks, which started to appear in the 14th century in Europe. (Not in the 10th, built by Gerbert d'Aurillac.)

Let's not neglect candle clocks. A Chinese poem written in 520CE by You Joanfu mentions a clock marked so that it could be used while burning to measure the passage of night time. The Anglo-Saxons credit Alfred the Great with creating the candle clock. He used squat candles (<5" high) marked at 1" intervals to mark time.

The hourglass was also a common method of measuring time, the earliest depiction of which is in a 1338 painting by Ambrogio Lorenzetti.

The earliest mechanical clock, a clock that did not use water or sand or candles, that used a predictable motion due to the escapement and a pendulum, did not appear until the early 1300s. Norwich Cathedral had a tower clock constructed in the early 1320s. The first known municipal clock that struck on the hours was in Milan in 1336. Over the next few decades, mechanical clocks appeared all over: Old St. Paul's Cathedral, Salisbury Cathedral (still has many original parts!), Wells Cathedral (still with its original face), etc. Detailed descriptions of clock designs by Richard of Wallingford (1292 - 1336) and Giovanni de Dondi (c.1330 - 1338) still exist, though the many clocks they built are long gone.

A king who developed his own timepieces made from candles? He sounds like someone worth looking into.

Tide Dials

The Bewcastle Cross has what is considered the earliest surviving English sundial. It is actually a "tide dial." The "tide" part of the name comes from the Old English tīd, used to refer to hours, specifically canonical hours. The canonical hours are the specific times of day that require prayer. These times of prayer are also called "offices" or "divine offices," because they are an official set of prayers. The shift from "tide" to "hours" came after the Norman Conquest in 1066, when the Norman French hour replaced the Old English term.

So the tide dial shows the specific times when prayers are encouraged (but may also display hours of the day).

This is not to say that they did not recognize additional segments of the day. If you look at the illustration, you will see the words Prime, Tierce, Sexte, Nones. These refer to the First, Third, Sixth, and Ninth hours of the day. Prime was the first hour of daylight, so sunrise, and the time for the first set of prayers. The next set of prayers did not have to take place until the Third hour after that; three hours later, Sexte prayers took place, followed by Nones and finally Vespers, or evening prayers.

Because the length of time between sunrise and sunset varies throughout the year, the time between prayers was not precisely 180 minutes. With more regular timekeeping, fixed hours were designed for these times. Tomorrow I'll show you the canonical hours that are still used today.

https://en.wikipedia.org/wiki/Tide_dial#Bewcastle_Cross

The Bewcastle Cross

The Bewcastle Cross is one of two stone monuments from the same era with similar iconography. Standing 14.5 feet high (it would be higher, but the actual cross top has broken off), it dates from the 7th or early 8th century, like the Ruthwell Cross (see the previous post).

Also like the Ruthwell Cross, it is covered with fine carving, Christian symbols, and runic inscriptions.

Images include John the Baptist holding a lamb, and Christ with a halo being held up by two beasts, similar to Christ being recognized as dominant over beasts on the Ruthwell Cross.

One difference from Ruthwell is that we have some idea of who made the Bewcastle Cross. A heavily weathered inscription has been interpreted by some to say "This slender pillar Hwætred, Wæthgar, and Alwfwold set up in memory of Alcfrith, a king and son of Oswiu. Pray for their sins, their souls". This may refer to Egfrid, who was king of Northumbria from 670 until 685. Presumably this dates the pillar to after 685.

One feature of the Cross that distinguishes it from Ruthwell is the earliest known English sundial. We will delve into that tomorrow.