Why Timekeeping?
The History of Timekeeping 🏆
Course 2 · Chapter 1 · Why Timekeeping? Scope & Sources
Every day in Edinburgh, except Sundays, a gun is fired from the Castle at one o'clock. It began in the 1860s so that ships in the Firth of Forth could set their chronometers by it (check the date), and it still sounds across Princes Street today. The gun is a good place to begin a history of timekeeping, because it shows what the subject is really about: not clocks as objects, but agreement. A clock is only useful if many people trust it and set themselves by the same signal. This chapter explains why people needed to measure time, what nature offered them to start with, the main kinds of device the course will follow, and how to tell solid evidence from legend.
Why Measure Time at All?
For most of human history the need was practical rather than precise.
Farming and seasons
When to sow, when to expect floods, when to move the flocks. The need was for a calendar, not a clock.
Religion and ritual
Prayers, festivals and sacrifices had to happen at the right moment. Much of the early demand for accurate time came from priests and monasteries.
Trade, law and travel
Markets, courts, sailing and later railways all needed people in different places to agree on when something would happen.
Nature's Own Clocks
Before any device, there were three cycles that everyone could see.
| Cycle | What happens | What it gave people |
|---|---|---|
| The day | The Earth turns once, so the Sun rises and sets | The basic unit; the position of the Sun or a shadow marks the hours |
| The month | The Moon runs through its phases in about 29.5 days | The first calendars; the word "month" is related to "moon" |
| The year | The Earth circles the Sun, giving the seasons in about 365.25 days | The farming and festival calendar |
The trouble is that these three do not fit together neatly. A lunar month is not a whole number of days, and a year is not a whole number of months or days. Much of the story of calendars (Chapter 3) is a long series of compromises over this mismatch.
The Main Kinds of Device
The course follows a small number of ideas through time, each solving a problem the last one left.
| Device | Principle | Main weakness |
|---|---|---|
| Sundial | The Sun's shadow moves across a marked surface | Useless at night or under cloud, and the hours shift with the seasons |
| Water clock | Water flows at a steady rate, so its level marks the time | The flow varies with temperature and pressure |
| Mechanical clock | A falling weight released in small steps by an escapement | Poor accuracy at first; needed constant resetting |
| Pendulum clock | A swinging weight keeps a steady beat | Cannot be used on a moving ship |
| Marine chronometer | A spring-driven watch made resistant to motion and temperature | Costly and delicate |
| Quartz and atomic clocks | A vibrating crystal or atom gives a very regular beat | Need coordination to stay in agreement with the Earth's slightly irregular rotation |
What the Course Covers
| Chapters | Theme |
|---|---|
| 2–3 | Shadows, water and the first calendars |
| 4–5 | The mechanical clock and the pendulum |
| 6–7 | Longitude at sea; railways, time zones and modern clocks |
| 8 | How time is kept today |
Record, Legend and Round Numbers
Three kinds of claim need different handling in a subject full of "firsts".
Record
Surviving objects, dated documents, and accounts by named people who saw the thing. These carry the most weight, but they survive unevenly.
Legend
Stories such as a single inventor producing a clock in a flash of inspiration. Real clocks emerged over generations, and "the first clock" is usually a claim about the earliest surviving evidence, not the earliest clock (check any such claim).
Round numbers
Dates like "the 14th century" or "about 1300" are honest about uncertainty. Be wary of a precise date for the start of something gradual.
Where to See and Read More
- Museums. The National Museum of Scotland in Edinburgh, the Science Museum in London and the Royal Observatory at Greenwich all hold historic clocks and instruments (check current displays).
- Public clocks. Church towers, town halls and railway stations are part of the story, and the Castle gun is one more.
- Specialist societies. Clock and watch societies publish histories and guides for beginners.
- Old sundials. Many Scottish houses and churchyards carry one, often with a motto about time.
- A home experiment. A stick in the ground and a notebook make a working sundial, and the course returns to this in Chapter 2.
Exercises
In three sentences, explain why a purely lunar calendar drifts out of step with the seasons, and name one way calendars have dealt with the problem.
Sort these into record, legend or round number: (a) a dated entry in a monastery account book recording payment for a clock; (b) the story that one named man invented the clock in a single moment; (c) "mechanical clocks appeared in the later 14th century".
Push a stick upright in the ground (or use a fence post) on a sunny day. Mark the end of its shadow at three times, such as 10:00, 12:00 and 14:00, and write two sentences on how the shadow's length and direction changed.
Quick Reference
- Why measure time: farming, ritual, trade, law and travel
- Natural clocks: the day, the lunar month (about 29.5 days), the year (about 365.25 days)
- The mismatch: the three cycles do not divide evenly, so calendars are compromises
- Devices: sundial, water clock, mechanical clock, pendulum clock, chronometer, quartz and atomic clocks
- Handling sources: separate record, legend and round numbers
- First stops: museums, public clocks, specialist societies
- Check: the date of the Castle gun, the figure for the lunar year, claims about "firsts", current museum displays
Next chapter: Sun, Shadow and Water, which covers sundials, water clocks and how the day came to be divided into hours.