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The subject of this series of lectures is horology, the science of measuring time, and we'll be looking at a few basic concepts in this lecture.
The measurement of time has come a long way since ancient times. It began with such devices as the sundial, where the position of the sun's shadow marked the hour. Daylight was divided into twelve 'temporary hours' - these temporary hours were longer in the summer and shorter in the winter, simply because the amount of daylight changes with the seasons.
The earliest sundial we know comes from Egypt. It was made of stone and is thought to date from 1500 BC. Sundials were used throughout the classical world, and with time, evolved into more elaborate devices that could take into account seasonal changes and geographical positioning and reflect the hours accurately, no matter what the time of year. This was quite an achievement in technology. Today, sundials can be seen as decorative pieces in many gardens.
In the eleventh century, the Chinese invented the first mechanical clocks. They were large and expensive, and certainly not intended for individuals. However, this is the type of clock we are familiar with today. There have been many developments in clocks and watches since then, and they have been greatly improved, but if your dock or watch makes a ticking sound, then it could well be based on the mechanical movements the Chinese developed a thousand years ago!
However, timekeeping has moved on from the mechanical clock. Time has become so important that there is a series of atomic docks around the world which measure International Atomic Time. Even though many COuntries have their own calendars, globalisation has made it essential that we measure time uniformly, so that we know, for example, that when it's 6 a.m. in the United Kingdom, it's 2 p.m. in Beijing. This standard was set in 1958. Now these atomic clocks are situated in over seventy laboratories all over the world.
There is so much to cover about the development of time measurement that l'd like to refer you to the reading list. The core text is The Development of Time: Theory and Practice, but there are many other useful texts. A good grounding in the subject is given in Understanding Time by J. R. Beale. Although some sections lack detailed analyses. it does offer a good foundation. Also Time: Concepts and Conventions is quite a useful read. You might think from the title that it's about the philosophy of time, but this isn't the case. Rather. it gives a good description of how different countries have different approaches to time in terms of calendars and days. Lastly. The Story of Time by David Harris analyses time in great detail, and I would recommend this book if you are aiming to specialise in horology.
Now, we're going to continue with an in-depth look at lunar and solar cycles.
