Mapping Time: The Calendar and Its History

Rating:
Summary: Past Perfect
Review: Designing calendars is one of the more difficult tasks that human beings have set themselves. You first needed to -determine- the lengths of the cycles of the solar year and the lunar month. This was not an easy task, and it was not achieved until well into recorded history.

The various cycles don't fit into each other particularly easily, either. With a solar year of just under 365.25 days, and a lunar month of just over 29.5 days, you aren't going to get it to come out even in the short run. You can stick with the sun and ignore the moon --- the solution of the Roman calendar fixed by Julius Cæsar. You can go with the moon, and leave the seasons to fall where they may --- as Muhammad, the desert-dwelling prophet of Islam, chose.

Or you can try to keep the moon and sun tied together, necessarily loosely. This requires a number of cumbersome kludges, as the Babylonians, the Jews, the Chinese, and the Christians who fixed the date of Easter all discovered. These calendars took a lot more thought than the ones that simply discarded one or the other heavenly lights, and rank among the most intricate and intriguing works of ancient astronomy.

This book contains a complete listing and description of the several solutions people have come up with to this seemingly intractable problem of arithmetic.

Rating:
Summary: An intriguing compendium of obscure lore
Review: Designing calendars is one of the more difficult tasks that human beings have set themselves. You first needed to -determine- the lengths of the cycles of the solar year and the lunar month. This was not an easy task, and it was not achieved until well into recorded history.

The various cycles don't fit into each other particularly easily, either. With a solar year of just under 365.25 days, and a lunar month of just over 29.5 days, you aren't going to get it to come out even in the short run. You can stick with the sun and ignore the moon --- the solution of the Roman calendar fixed by Julius Cæsar. You can go with the moon, and leave the seasons to fall where they may --- as Muhammad, the desert-dwelling prophet of Islam, chose.

Or you can try to keep the moon and sun tied together, necessarily loosely. This requires a number of cumbersome kludges, as the Babylonians, the Jews, the Chinese, and the Christians who fixed the date of Easter all discovered. These calendars took a lot more thought than the ones that simply discarded one or the other heavenly lights, and rank among the most intricate and intriguing works of ancient astronomy.

This book contains a complete listing and description of the several solutions people have come up with to this seemingly intractable problem of arithmetic.

Rating:
Summary: A little heavy on the facts and too light on the story
Review: If expanded, this would make a good reference text. As a leisure read, it's weighed down by a fact-heavy writing style that makes it read like a bulleted list. While the information is great (if occasionally slightly inaccurate) and the additional reference material is useful for context, it lost my interest pretty early on, and I only finished it out of a grudging desire to just be done with it.

Great reference material; not very re-readable.

Rating:
Summary: one of the best books I read in 1999
Review: In this well-illustrated book, the author accurately presents lunar and solar calendars. A history of the Egyptian, Mayan, Chinese, Jewish, French Republican, Roman, prehistoric and present-day Gregorian calendars is provided. The author has also included commentaries about astronomy, writing, counting, the week, the month, the year and calendar reform. An excellent readable reference on a fascinating subject for the interested reader.

Rating:
Summary: Past Perfect
Review: One of several books written in anticipation of the millennium, "Mapping Time: The Calendar and Its History" by E. G. Richards suffers from an especially heavy burden of typographical errors. As can be seen on the author's own web page, the address of which also is incorrect, there are hundreds of errors, some of which affect the accuracy of the account. For example, on page 208, January 1 came to mark the beginning of the Roman civil year in 153 BC, not 158 BC, and was in response to the Second Celtiberian War in Spain. Rather than wait until the middle of March for consuls to assume office, the new year was moved to the first of January so the Roman commander could depart with his legions that much sooner. It is a pity that so many errors compromise an otherwise informative history. Until they can be corrected, a better introduction to the calendar is "The Oxford Companion to the Year."

Rating:
Summary: Erudite But Fun
Review: This is a nice examination of the different calendars and methods of mapping time that humans have employed over the centuries. On the surface it has the air of a dusty reference book, but inside the author is often witty and amusing as he covers the histories and backgrounds of different dating systems. I'm especially impressed by his inclusion of the different algorithms used to calculate dates, of Easter for example, which are marvelously complex. Most readers will never have occasion to use these algorithms, but its nice to know they're there. I also appreciated the charts and the glossary of the more obscure calendrical terms.

Rating:
Summary: Erudite But Fun
Review: This is a nice examination of the different calendars and methods of mapping time that humans have employed over the centuries. On the surface it has the air of a dusty reference book, but inside the author is often witty and amusing as he covers the histories and backgrounds of different dating systems. I'm especially impressed by his inclusion of the different algorithms used to calculate dates, of Easter for example, which are marvelously complex. Most readers will never have occasion to use these algorithms, but its nice to know they're there. I also appreciated the charts and the glossary of the more obscure calendrical terms.

Rating:
Summary: Interesting but flawed
Review: Very interesting history of the major calendar systems used around the world, both in the present day and in the past. It also gets into the mathematics of how to convert between calendar systems, including algorithms suitable for computer programming. Unfortunately, there are numerous typographical errors in the narrative and in the algorithms! The word "temperature" where the author clearly meant "temperate", substitution of "*" for "-" in a formula, etc. So far, I have been able to correct the formula for computing the day of the week and the formula for computing the date of Easter. I'm not looking forward to tackling the other algorithms. Did anyone proofread this before it was printed? Maybe the publisher could put up an errata sheet on their web site.

Good for the history, but be prepared to do some algebra if you want to use the algorithms.