Following up on my post of a couple of days ago, I saw a further article in Wired about the proposed new Hanke-Henry Calendar.

What is interesting is that when I looked at this Wired article, they had a poll asking whether readers wanted to retain the existing Gregorian calendar or change to the HH version. To my surprise almost two-thirds for the almost 20,000 voting said they would prefer the new Hanke-Henry Calendar.

Hmmm … Maybe! I bet if we went there most of this support would vanish. Such, in my experience, is the way of people.

While I think the Hanke-Henry Calendar is interesting, and would probably support it, I continue to have two reservations.

Firstly, it starts the year (and therefore every week) on a Sunday which, as I mentioned before, is counter to the international standard on dates (ISO 8601) — but when did that ever matter to Americans? However this is really easily fixed by starting the year on a Monday, although that does mean the new calendar couldn’t be introduced until 2018 without moving the names of the days. I see no problem with a 2018 start date as that will give everyone time to adjust.

(Out of interest, using Henry & Hanke’s method Christmas Day would always be on a Sunday, whereas using my Monday method Christmas Day would always be on a Monday.)

Secondly, and more seriously, while Henry & Hanke do away with the annoyance of leap years and leap days, they have to introduce an alternative to ensure the calendar keeps roughly in line with solar time as the years pass. So they introduce the leap week — an extra week added at the end of the year every 5 or 6 years. That’s fine, but is it every five years, or every six? Actually it is some arcane combination; there is no good (read, easy for Joe Public) method for determining when to add the leap week.

According to the Wired article the leap week is “inserted into years starting or ending on a Gregorian-calendar Thursday” which “would almost perfectly account for Earth’s 365.2422 day-long orbit around the sun”. This is unutterable madness! Why base the leap weeks on the “old” calendar we’re replacing?

Currently there is a simple method for calculating what is a leap year. A method which Joe Public is capable of understanding. But the Hanke-Henry system would leave people with no clue as there is no simple pattern to what would be leap week years. How many people are going to keep track of the “old” calendar just to calculate leap week years? Answer: none! Within a few years people will have no clue when leap week years are (the calculation is arcane, to say the least), just as now almost no-one can calculate when Easter falls despite that it follows a simple rule.

But I reckon this too can be pretty well fixed with a simple algorithm. How about this? … In the new calendar every year is 364 days (52 seven day weeks), except when the year is divisible exactly by 5 when you add the leap week unless it is also a century or half-century year. So years 2005, 2010, 2015, 2020 and so on would be leap week years; but not 2000, 2050, 2100, 2150 etc. According to my calculation that runs about as close as this calendar can to true, being just a couple of days out after 500 years. That’s about as good as you’re going to get given that with a 7 day leap week system the variations from true solar time can be up to a week or so. This way people will know very easily what are leap week years and what aren’t. No need to perpetuate the calendar we’ve tried to replace.

(Actually after 500 years the calendar is maybe lagging solar time by slightly too much, on average, so you might want to add back the leap week in 2500. But that is maybe a refinement too far at this stage.)

Now who would like to sort out the moveable feat known as Easter? Shall we just adopt the Pagan feasts?

Did you change your calendars yesterday for the bright new 2012 versions?

I bet you didn’t! At at least not to the overhauled calendar being advocated by Richard Henry and Steve Hanke of Johns Hopkins University in the USA, because the proposed Hanke-Henry Calendar is a bit radically different: it has a reformed pattern of two 30 day months followed by a 31 day month, four times a year. So the rhyme, “30 days hath September, April, June and November” would be revised to “30 days hath September, June, March and December”.

This means that every year would be composed of a regular 52 seven-day weeks, and every date will always fall on the same day of the week — like Christmas Day would always be, say, a Sunday. It gets rid of the silliness of leap years and of remembering how many days each moth has.

So who sees the problem? Surely if it was that easy it would have been done centuries ago.

Yes, that’s right the Hanke-Henry Calendar produces a year of just 364 days. Whereas the Earth year is 365.2422 days (hence our need for a leap day every four years to correct for that almost ¼ day error). So what do they do? Yes, that’s right! They impose not leap days, but leap weeks by adding an extra week to the end of December every 5 or 6 years. GOK how they’d cope with the moveability Easter!?

There’s another flaw, which the Scientific American article doesn’t pick up on. Hanke and Henry want their calendar to start with 1 January on a Sunday (as 2012 is, and which will next occur in 2017). The only problem is that the International Standard on dates (ISO 8601, and see also the Wikipedia entry) decrees that the week starts on a Monday and that week 1 of the year is the first week containing at least 4 days (which turns out to mean the week containing the first Thursday of the year). It’s that “week starts on a Monday” rule that is the killer. Thanks to 2012 being a Leap Year the next year when 1 January is a Monday is 2018. Hanke and Henry don’t want to wait that long! But it would give time for everyone to agree to the idea and get their ducks lined up.

It’s an interesting and actually quite a logical idea, but to be honest I cannot see it catching on. If we thought the brouhaha over Year 2000 was painful, this would be ten times worse as every date algorithm would have to be not just checked but actually changed. And in the 11 years since Year 2000 the electronic world has expanded ten-fold, maybe a hundred-fold, beyond what it was in 2000. Business would never stand for what would be a hugely complex change — although it might help the unemployment figures.

All those who’d like to try this calendar say “Aye”.