History of Clocks

Here we outline the evolution of domestic clocks.

In the history of clocks and time-keeping, the earliest clocks were driven by water; the Roman 'horologium'. This term was later applied to the earliest mechanical clocks, which indicated time by sounding a bell each hour. This kind of 'horloge' became called a 'clocca', from the Latin for 'bell'. By the 14th century, this had evolved to 'clocke' in English.

Once the mechanism was developed to indicate the time visually, this new part was called the 'watch', taking its name from the parts of a day as used to manage sentries and sailors. If a timepiece struck the hours and showed the time, it was thus called a 'clock-watch'.

Most early mechanical clocks were driven by the fall of weights.

The technological development, which made the first reliable mechanical clock, was the verge escapement, invented about 800 years ago. The escapement impulses the foliot to keep it swinging. The wheels in a clock have the appropriate number of teeth to ensure the hands progress around the dial at a rate matching the actual passage of time.

Augsburg and Nuremberg were at the centre of European clock making. Some fabulous clocks were made in the 15th and 16th centuries. England was very slow indeed to come to quality clock making, but in the late 17th and the 18th centuries the English led the world in timekeeping developments.

Domestic clocks began to appear in British houses in about 1600, and were 'chamber clocks', of the 'lantern' type. The name 'lantern' may come from their appearance, or else is a corruption of the word 'latten', meaning brass. A hook on the wall supported them, and the driving weights hung down below them on ropes, later chains. They indicated the time, struck the hours and sometimes had an alarm. The early ones did not have a pendulum. After the pendulum was invented in 1657 lantern clocks were made with pendulums.

It is easy to underestimate the effect of the application of a pendulum to a clock. Suddenly instead of timekeeping to about 20 minutes a day, it was possible to achieve a minute a day. Over the next hundred years saw English developments lead the world in timekeeping, culminating in the marine chronometer, masterminded by John Harrison.

Lantern clock movements evolved into the longcase clock because with the weight of the movement and the driving weights it was safer to mount it in a tall case. Early cases were probably made by the coffin makers. The movement however did not have a long pendulum, and took the form of a table clock movement (often called a bracket clock). When the anchor escapement was invented in about 1671, it had a smaller angle of swing, and so a longer pendulum could be used in a narrow case. The longcase clock as we know it today, was born.

Spring-driven clocks appeared in the mid-15th century. These posed new technical challenges; the springs gave out a lot of power when freshly wound and got weaker as they unwound. They also produced power unevenly as they could not be made with great precision. A conical pulley between the spring and the gear train to compensate for the reduction on power as the spring unwound was called the fusee. In 1525 Jacob the Zech made the first recorded clock with a fusee.

The term 'grandfather' clock, and the variations for smaller longcase clocks such as 'grandmother', only date from 1876 when an American, Henry C Work, published a song 'My Grandfather Clock'.

The main thrust of work in time keeping improvements centred in the development of the escapement. The anchor escapement is still in use today, and is capable of adequate performance for domestic clocks. Ideally the escapement should interfere with the pendulum or the balance in a watch as little as possible. Variations in power to the escapement from the spring (through the gear train) should be kept as small as possible if not eliminated.