Mapping Time: The Calendar and its History Book

The passage of day followed by night is so definite that few of us bother to think about calendars and just take them for granted. And yet, as E.G. Richards shows in his fascinating account of how time was mapped, calendars are not at all straightforward. Calendars are essentially human constructs, as Richards quotes "God made the days and nights but man made the Calendar". A calendar is an attempt to make sense of the chance events during the creation of the solar system which determined the variations in the Earth's rotation and orbit around the Sun. Many different calendar systems have been invented by various cultures and societies around the world over the last few thousand years. Some have laboriously constructed huge stone calculating machines like Stonehenge in England; others make do with much simpler devices. My own favourite is a string calendar from Sumatra--a square plate with 30 holes and a piece of string to thread through a hole a day. But how do the Sumatrans know when a year is up? Without calendars modern life would be chaotic and highly dangerous. As Richards points out: "international trade would be almost impossible" without some uniformity. The extraordinary thing is that despite the proliferation of different calendars, there has been international agreement over the use of just one, which happens to be the Gregorian calendar. E.G. Richards is a an English academic biophysicist, whose interest in calendars was sparked off by writing a computer program to convert dates from one calendar to another. Fortunately, after many years of research he has compiled this fascinating book for the general reader. The three parts of the book cover the theory behind calendars, their original variety from different societies over the ages, and finally the tricky business of converting from one calendar to another. There is something here for everyone although you will need to be fairly dedicated to negotiate some of the more mathematical parts. Various appendices provide astronomical constants etc., and there is a most useful glossary, further reading list, and index. With the millennium in the offing, Richards reminds us that we will be celebrating the wrong date--January AD 2000 "is only 1999 years from the start of the Christian era, which began on 1 January of the year AD1, there being no year 0".Read More