
The Death and Life of the 13-Month Calendar - skinofstars
http://www.citylab.com/work/2014/12/the-world-almost-had-a-13-month-calendar/383610/
======
Tossrock
"The International Fixed calendar sucked the personality out of marking time,
making every week and month as predictable as humanly possible. [...] It's an
impossible feat that doesn't need pulling off and, thankfully, no one is
trying to anymore."

Spoken like someone who's never had to write date handling logic. Having
"personality" in your calendar system is a bug, not a feature. I feel
confident that we could maintain our overall levels of personality/joie de
vivre/je ne sais quoi by spending less time dealing with an incredibly
arbitrary calendar system and more time doing things we actually enjoy.

~~~
tempestn
A very small percentage of the population ever has to write date handling
logic. For the rest, things "just work", thanks to those few.

Besides, even as a member of that small group, I like the variety of the
current calendar, inefficient as it is.

~~~
32bitkid
One has to admit that it complicates even trivial communications about days
and times. Even questions like "What's the date of friday next week?" can't be
quickly answered. Or "Is Nov 12th on the weekend?" I feel these are practical
things that _most_ people would _like_ to easily reason about, but can't.

It imperial units for days; or like trying to do math in a numerical system
where each significant digit has a different random radix. Does it have
variety? Yes... Is even remotely fun to do anything practical with? No.

~~~
chongli
_Even questions like "What's the date of friday next week?" can't be quickly
answered._

Fortunately we don't have a very pressing need to answer these sorts of
questions; we have tools galore to handle them for us: smartphones, calendars,
messaging apps, meetup etc. Topics like these often remind me of one of
Einstein's more famous quotes:

 _[I do not] carry such information in my mind since it is readily available
in books. ...The value of a college education is not the learning of many
facts but the training of the mind to think._

We used to spend an enormous amount of time teaching our children mathematical
tricks which have now all been made completely obsolete by the scientific
calculator. Only the most rudimentary of arithmetical strategies have
survived, if only for the fact that it's still a little inconvenient to reach
into your pocket when scanning and counting objects with your eyes.

~~~
rtpg
I disagree, many times people are trying to coordinate and one person says the
8th thinking it's a friday, but it's actually thursday. So some people think
they were talking about the 8th, others talk about it like it were the 9th,
and there's confusion all about.

Casual calendar coordination is really easy to mess up in the current state.

------
IgorPartola
This. I have been thinking about this for a long time. Basically, 364 days are
exactly the same, and what is currently December 31st would become the Year
Day where everyone has it off. If it's a leap year, there'd be two Year Days.
Simple, efficient, and easy to understand.

Birthdays being on the same day of the week is a poor objection: your birthday
already falls on a weekday much more often then not, and chances are you
celebrate it on the weekend before or after. We'd lose variability in holidays
that are "last Thursday of the month": they'd just be on a specific date every
year.

One nice thing we'd gain is that the phase of the moon would shift much slower
with respect to our calendar (the moon doesn't do a Year Day). I suppose some
superstitious healthcare workers might object to this. If you think about it,
there are many more things naturally tied to 28 days than 28/30/31.

~~~
beefman
Actually the synodic month is closer to 365/12 days than to 28 days, so the
13-month calendar drifts slightly faster with respect to phases of the moon.

------
msoad
Fun fact:

The arabic calendar which is based on Moon movements used to have an extra
month every four(?) years to adjust the season changes. It was called Nasi'
month. But after a Quran Sura published that prohibited this month Arabic
calendar lost it's accuracy for seasons.[1]

The Iranian Calendar that is based on sun movements was safe from this Sura
because it didn't have an extra month but an extra day each five years.[2]

[1]
[http://en.wikipedia.org/wiki/Nasi%27](http://en.wikipedia.org/wiki/Nasi%27)

[2]
[http://en.wikipedia.org/wiki/Iranian_calendars](http://en.wikipedia.org/wiki/Iranian_calendars)

~~~
cauterized
The Hebrew calendar (also lunar) still does this - a leap month in (IIRC) 7
out of every 19 years.

------
dredmorbius
Eviatar Zerubavel's _Seven Day Circle_ is a detailed and complex history of
time telling.

It really helps to understand that in a calendar we're trying to measure three
distinct (and variable) cycles, none of which fits precisely into the others,
and each of which imposes its own rhythms on human life. Attempts to break
each from the current 7/12/365 basis have virtually all failed.

The first is the Earth's rotation about its own axis -- different when
measured with respect to the stars or the Sun.

The second is that of the Moon about Earth.

The third is of the Earth about the Sun.

We overlay them on each other and pick rough correspondences.

Much of the division has to do with Babylonian time reckoning, based on 360,
and its factors: 2 * 2 * 2 * 3 * 3 * 5. From that you find 2, 4, 5, 6, 8, 9,
10, 12, 15, 18, 20, 24, 30, 45, 72, 90, 180, and 360. A seven-day week doesn't
fit this directly but is close (between 6 and 8), and a 30-day month also fits
well.

Then you come to realize that all timekeeping, _especially_ that which picks a
specific starting point, is arbitrary.

The book also details several attempts to change the system, particularly
following the French and Russian revolutions (oh, and the reason for that
being the October revolution -- and there's the question of what was the last
nation to adopt the Gregorian calendar, and why the output of 'cal 1752' is
what it is ... and why even _that_ is arbitrary (it depends on where you're
specifying the date).

[http://www.powells.com/biblio/61-9780226981659-2](http://www.powells.com/biblio/61-9780226981659-2)

~~~
canjobear
It's not clear that the rotation of the moon has much significance in modern
life any more, so maybe the problem can be simplified.

What was the significance of cycles of the moon in the past, anyway? The main
thing I can think of is astrology. Can tides be predicted accurately using
phases of the moon?

~~~
triangleman
Month = "Moonth"

Aside from the female menstrual cycle, the gestational cycle is also in line
with the moon: A baby is brought to term in 10 moons or 280 days (9 months or
so).

You would also have an easy way for disparate peoples to mark time, since in
the past there was no such thing as telegraphs or even pony express.

~~~
xorcist
That's only because we have a weird method for calculating pregnancies, for
historical reasons.

A human pregnancy is around 266 days +- 16. The reason for 280 days or 9
months is because that measures the time span since the last menstruation, not
since conception.

(I was personally a bit surprised by this when expecting our first child. It's
one of those things you apparently know about but still use "9 months" as a
bit of a fixed expression.)

------
0x45696e6172
This seems to be slightly inferior to the Pax calendar[1].

The Pax calendar has another very cool property, which is that the weekdays
are always in sync with Gregorian calendar. This is done by carrying over
leapdays until you have one full week accumulated, which is then inserted as a
leapweek, in the same way we insert leapdays in the Gregorian calendar.

[1]
[http://en.wikipedia.org/wiki/Pax_Calendar](http://en.wikipedia.org/wiki/Pax_Calendar)

------
kcovia
Also in alternate calendars:

 _Each day in the Republican Calendar was divided into ten hours, each hour
into 100 decimal minutes, and each decimal minute into 100 decimal seconds.
Thus an hour was 144 conventional minutes (more than twice as long as a
conventional hour), a minute was 86.4 conventional seconds (44% longer than a
conventional minute), and a second was 0.864 conventional seconds (13.6%
shorter than a conventional second)._

[http://en.wikipedia.org/wiki/French_Republican_Calendar](http://en.wikipedia.org/wiki/French_Republican_Calendar)

------
ChuckMcM
When I was at Intel they marked everything in Work Weeks, that was essential
for scheduling things like chip fabrication plants. It took a little while to
get used to but then it made computing questions of 'when' quite straight
forward.

I'm personally in favor of a more structured system like this, my wife on the
other hand is viscerally opposed. If that schism is widespread I expect the
next calender change to occur when the known world is ruled by an emperor :-)

------
SixSigma
"We've always done it this way" are the seven most expensive words in
business. Catherine DeVrye (2000)

------
frogpelt
In addition to the 13 month calendar, I wish the year started in March or
April. The beginning of Spring* makes more sense for a new year than the
middle of winter.

*I realize this is only true in the northern hemisphere, but 90% of the world's population lives in the Northern Hemisphere. The other 10% can start their year in the Fall.

~~~
gohrt
This is how the calendar originally worked (DECemeber is 10th month), until
politics intervened in ancient Rome.

~~~
tjradcliffe
The Julian calendar typically started the year on the 25th of March (Lady Day)
at noon (prior to clocks it was much easier to reckon mid-day than mid-
night... navies kept this practice at least into the 1800's). This was true
into the 1600's in parts of Europe and North America.

------
drdeadringer
Reading this article is my first exposure to this 13-month calendar [I don't
count the Simpson's episode]. I'm glad for the read and found it very
interesting.

------
imroot
This is a little bit different from the accounting 13 month calendar -- an
"Adjustment" month that usually falls in the next FY that the
accounting/auditors can do adjustments and still have 'true' dates on
everything.

Honestly, having another month to pay bills (and you know that nobody's going
to pro-rate everything down to 13 months) isn't really appealing right now,
nor would the additional overhead of two more payroll cycles.

Logically, it makes sense, though.

~~~
redblacktree
For what it's worth, I'm already paid for 26 pay cycles each year, and I work
at a company of 30k+.

------
latortuga
This would complicate anything that is paid for monthly, including but not
limited to: employee salaries, rent/mortgage, subscriptions, utilities, etc.
Do we just ignore Sol for those purposes or roll it into another month?

Having your birthday perpetually on a wednesday would also not be so much fun.
Perhaps "year day" could shift every year forward by 1 week day - year day
could be Monday and then Jan 1 of the next year could be a Tuesday etc.

~~~
estel
Don't some companies already run salary in thirteen four week periods? I've
worked at at least one that did.

~~~
jeffasinger
I'm not 100% sure, but in the US, this is relatively rare, as it's required in
most situations to be paid at least 2 times per month.

I think all but 5 states have laws dictating pay frequency, and in most cases
they require at least two times a month pay frequency.

The most popular pay schedules tend to be 24, 26, and 52 times per year.

EDIT: This was supposed to be a reply to redblacktree. State law examples: \-
[http://www.dir.ca.gov/dlse/faq_paydays.htm](http://www.dir.ca.gov/dlse/faq_paydays.htm)
\- [http://labor.ny.gov/legal/counsel/pdf/frequency-of-pay-
frequ...](http://labor.ny.gov/legal/counsel/pdf/frequency-of-pay-frequently-
asked-questions.pdf)

~~~
aetherson
I would like you to explain to me what the situation is in which you imagine
that being paid every 2 weeks would result in you being paid less than twice a
month.

------
kijin
Using the same calender every year might work fine in America and some of the
Western European countries. (According to the article, Easter and Thanksgiving
can be given fixed dates in the 13-month calendar.) But many non-Western
cultures have holidays tied to phases of the moon. Chinese New Year would
still move around a lot from year to year, making it impossible to reuse last
year's calendar. Ditto for _Chuseok_ in Korea, which needs to coincide with a
full moon.

So yeah, this looks like a nice change, but it's not going to be completely
static from year to year in every culture.

Besides, I don't think it will completely eliminate the difficulty of figuring
out what date "next Thursday" is. We at HN tend to be mathematically
competent, so we can easily calculate multiples of 7 in our heads and subtract
a few without breaking a sweat. Most ordinary people, on the other hand, have
difficulty figuring out what date next Monday is even when it's Friday and you
just need to add 3. They'll just look it up in a paper calendar or their
mobile device.

------
seccess
Okay, but can we come up with a calendar system where the months September,
October, November, and December don't have the wrong names? It has always
bothered me that the prefix sept- means seven, but it is the ninth month, oct-
is for the tenth month, etc...

~~~
vorg
Have a 14-month year, then start the following year in March.

~~~
seccess
Sold. This could have the added benefit that every leap year we can get two
days off for new years eve, since people will be used to getting Feb 28th off
anyway ;)

------
narrator
There's also the ill-fated Soviet Revolutionary Calendar

[http://en.wikipedia.org/wiki/Soviet_calendar](http://en.wikipedia.org/wiki/Soviet_calendar)

~~~
midhir
And the similarly fated French Republican Calendar:
[http://en.wikipedia.org/wiki/French_Republican_Calendar](http://en.wikipedia.org/wiki/French_Republican_Calendar)

------
caio1982
Somewhat related: the other day (this week even!) my wife was puzzled by the
names of months and she asked me about the meaning of each. If you think about
it for a moment you'll figure most of them out, but in any case this is a good
summary:
[http://www.design.caltech.edu/erik/Misc/month_names.html](http://www.design.caltech.edu/erik/Misc/month_names.html)

------
Pxtl
It's brilliant, I love it! That said, I'd be happy just to see the Daylight
Saving time-switch left on the dustbin of history.

------
function_seven
From the article:

> Easter would fall on April 15 every year on Cotsworth's calendar

I don't understand why this would be. Can someone explain?

~~~
NoMoreNicksLeft
Easter is tied to the days of the week, it's always on a Sunday. So it's going
to be week-aligned.

This calendar aligns months with weeks. Months are always exactly 4 weeks.

~~~
function_seven
But Easter moves around quite a bit during the year, sometimes being on the
83rd day of the year (in 2008), sometimes on the 110th day of the year (2014),
and various dates between. I don't see how changing to a 13 month calendar
would affect the first full moon after the spring Equinox, since the lunar
cycle doesn't mesh with the solar one.

~~~
NoMoreNicksLeft
> I don't see how changing to a 13 month calendar would affect the first full
> moon after the spring Equinox, since the lunar cycle doesn't mesh with the
> solar one.

Just checked... you seem to be correct. The lunar calendar isn't aligned with
this well enough. While the equinox date is fixed, the first full moon after
that should bounce around by several days at least. Even allowing that it's
always the Sunday after that, it still seems as if it could fluctuate by a
week in either direction.

------
gtbcb
I love the idea of a 13 months calendar; however, you're birthday would be on
the same day every year :0/.

~~~
lanna
Unless you were born Feb 29, I guess everyone's birthday is on the same day
every year. Mine, for instance, is always on Sep 11, every single year.

~~~
ComSubVie
You're confusing day (Monday, ...) with date (12th Dec).

~~~
jamie_ca
He's pointing out that those stuck on a leap day are still stuck.

If you count by day-of-year when doing the conversion, though, it's the people
born new year's eve on a leap year that are impacted.

------
hasenj
Why do we even have a 7-day week?

7 and 28 are just as arbitrary as 12.

Why do we even have a solar year?

If the year was 100 days, we could have a whole year of summer.

~~~
drostie
You're not going to convince either the Christians or the Jews to do a week
that isn't 7 days long. That number is more or less fixed by the sizeable
minority who need it for the rest of their habits.

The solar year is convenient so that one can speak of "the average historical
weather for this month" and such... but it's true that many others have done
lunar calendars etc.

~~~
hasenj
Muslims use the lunar calendar for religious occasions (Ramada, Hajj, Eid) but
use the Christian, solar calendar (like the rest of the world) for everyday
life.

------
cvburgess
I really like this idea - it makes scheduling things a whole lot easier. I
also like the concepts of the one week month and "year day" \- for some reason
I feel like I'd get more pumped about year day than I'll ever get about new
years.

~~~
function_seven
I didn't see anything about a one-week month on there, but the diagrams sure
make it look that way.

------
cesarbs
I wonder what Jews, Seventh Day Adventists, and Sabbatarians in general would
think of this.

------
faehnrich
Lousy Smarch weather.

------
minikites
This makes more sense than switching to the metric system.

~~~
bharath28
Why? I'm curious.

------
gtirloni
Mars Inc. uses 13-period calendar for everything.

~~~
coleca
When I worked for Royal Ahold they used a 13 period calendar. The date logic
was much worse to manage because you still had the rest of the world and every
programming language and database that used the Gregorian calendar.

We had a single mainframe subprogram that managed the whole thing. It was
written in assembler and the few times it broke, the entire company stopped.
Financials, ordering, invoicing, everything. Eventually they rewrote it in a
more modern language, COBOL. This was in 2010.

------
dfar1
My birthday would always be on a Sunday!

~~~
tehaugmenter
Also for the superstitious there would always be Friday the 13th

~~~
johnnyo
Easy fix, just start the month on a Monday instead of a Sunday

~~~
vorg
Starting the week on Monday seems more common than Sunday for most countries,
I believe France does. And China and Japan name their days literally "Day 1"
for Monday, ... "Day 6" for Saturday, and "Day Sun" for Sunday.

~~~
MichaelBurge
This is wrong. Saturday in Japanese is 土曜日, which is like "Earth day".

There's also "Sun day"(Sunday), "Moon day"(Monday), "Fire day"(Tuesday),
"Water day"(Wednesday), "Tree day"(Thursday), "Gold day"(Friday), "Earth
day"(Saturday). So your claim is wrong in Japanese for every day except
Sunday.

If you see something written like 四日("4 day"), this refers to the day of the
month not the day of the week(for Japanese).

~~~
vorg
Chinese uses the numbers for days of the week, so 星期一,星期二,星期三,星期四,星期五,星期六,星期日
for Monday to Sunday. They can use 周 or 礼拜 instead of 星期.

I remembered Japanese copied the Chinese at something there, but, whoops, it
was the names of the planets that were copied. So the Chinese names of
Mars(火星), Mercury(水星), Jupiter(木星), Venus(金星), and Saturn(土星) are copied onto
the same days as planets that Romance languages name their days after.

~~~
saraid216
FYI, 日 is not "seven". It's "sun" or "day". It's almost like someone had a
sense of humor when they named that day.

My interpretation has always been that 日 is meant to represent "zero", but I
never put any thought into why they didn't just call it 星期零.

~~~
vorg
"星期日" is generally written Chinese, but in speech Chinese say "星期天" where 天
could mean "God" when the 7-day week was copied from "Christian" Europe. I
just found
[http://www.cjvlang.com/Dow/dowchin.html](http://www.cjvlang.com/Dow/dowchin.html)
to explain the history of Chinese and Japanese day names in detail.

I've noticed while living in China that, whereas Westerners like me virtually
always remember what day of week it is but often forget the date in the month,
Chinese are more likely to remember the day of the month and forget the day of
the week.

~~~
saraid216
Ah. I grew up in a Cantonese-speaking Christian family in America, so I've
never heard 星期天 used in speech at all.

Confusingly, the "seven luminaries" system in that article aren't just
referencing the planets: they're also the names of Sun, Moon, Fire, Water,
Wood, Metal, and Earth. I did get that sorted out by looking up Western
alchemical ordering for the planets, which is in the same order. Wikipedia
helpfully provides a table that includes the _old_ names for the planets as
well:

[http://en.wikipedia.org/wiki/Classical_planet#East_Asia](http://en.wikipedia.org/wiki/Classical_planet#East_Asia)

