Timekeeping devices

But how to keep track of the time when the sun was not shining, that is, during the nighttime or when the sky was overcast? This is the problem which gave rise to artificial timepieces not reliant on the sun or stars. 

What was needed was reference something else that worked at a constant rate day and night.

From antiquity to the end of our period, the most suitable force was that of gravity. Gravity powered most of the early timepieces aside from the sundial: namely, the water clock (filled with water), the hourglass (filled with sand) and the first mechanical clocks (driven by a suspended weight).  In pre-modern times, the only exception was the candle clock.  From the fifteenth century, the spring freed the clock from reliance on gravity, making possible table clocks as well as the first pocket watches. These were superseded in turn by electric, quartz and atomic clocks of the twentieth century. 

Although the mechanical clock seems at first sight complex, in essence the medieval European mechanical clock consisted of four components: (i) a weight drive harnessing gravitational energy; (ii) a mechanism (known as an ‘escapement’) controlling the release of that energy; and (iii) a mechanism for transmitting that controlled energy through a gear train to (iv) an indicating mechanism which marks out intervals of time (either by turning a dial or sounding a bell). 

Commentary: Howard Hotson (May 2024)