> On May 24, 2008, at 7:28 PM, Daniel Carrera wrote: >> The 12-month year comes from the Egyptians, but I don't know where >> the Egyptians got it from. My first guess would be because a month >> is about the same as a moon cycle, but the problem with that is that >> a 13-month calendar would fit a lot better (13 months of 28 days is >> only 1 day less than a year). > > > But a lunar month isn't 28 days -- it's about 29 1/2. And that gives a > figure nearer 12 than 13. For a long time, attempts were made to > reconcile these by various forms of brute force. The Jewish calendar > sticks in a 13th month about every other year. The ancient Roman > calendar tried something similar, but it got so messed up that Julius > Caesar decided to go to the artificial "months" we still use today. > The Islamic calendar still goes by true lunar months, and just forgets > about the solar year, so that it is constantly slipping compared to > the Western calendar.
Which is why basing units on physical constants is never universally successful in terms of getting nice round figures and relationships in quantitative analysis. Whichever constant is chosen (and often these turn out not to be constants) others are not going to fit. Matching the unit system to the number system seems sensible. Trying to base measurement on a specific physical quantity/constant or set of them is only going to have limited success. The day as a unit of time makes much more sense than say a specific dimension of the Earth as a unit of length because we organise our lives around days but not around any specific length. > -- > John W Kennedy > If Bill Gates believes in "intelligent design", why can't he apply it > to Windows? Maybe he believes it's evolving ;-) Ian --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
