Thursday, 25 October 2012

The problem with the 24-hour clock

The problem with the 24-hour clock is the teens.  Not '1300', and not -- speaking from experience -- 1400 or 1500.  But '1600' makes me think, even after many years familiarity with the system, of '6 O'Clock', not 4pm and '1800' brings '8 O'Clock' to mind rather than 6.  Oddly, as I think about it, I don't really have this problem with 1700 or 1900; and obviously the 20s don't correspond to a 'pm' timeslot.  I wonder why the ambiguity is limited, for my stubborn brain, to those two times?


Archie_V said...

The odd thing about the 24-hour clock, I've found when editing, is that people use it for precision yet still seem to feel it needs explaining - especially for the early hours.

A couple of examples from a very quick Google:

At 0130 hours on the morning of April 28, 1944...

I'd change that to "At 1:30 a.m. on April 28, 1944", because we semiconsciously gloss "a.m." as "in the morning" anyway.

About 0130 hours this morning, Kirwan Heights Fire Department and Fire Rehab were dispatched...

Here, the military precision of "0130 hours" is already on its knees by the time we get to it because of that wonderfully imprecise "about". And again, the writer felt the need to specify "morning", perhaps because they were worried - probably with good reason - that some readers might think "0130" is lunchtime. Wouldn't "At about one thirty last night, Kirwan Heights Fire Department...." have been clearer, more natural, less fussy and yet just as precise?

I know that all this has very little to do with your point about 1400 and 1600, Adam, which are also my two blind spots (especially when minutes are involved - 1635 is twenty-five, when, exactly?), but we seem to be even less comfortable with the 24-hour clock in general than with the metric system of weights and measures. Even decimalisation was assimilated very quickly, even by old people for whom "seven and six" was second nature, while "thirty-seven and a half pee" was suspiciously foreign-sounding. But only 18 months later nobody was confused any more. That's never happened with the 24-hour clock - even decades after it was introduced for bus and train timetables and flight-departure boards that we see every day.

"1600 hours" should make things easier and less confusing but actually just causes people to stumble and doubt.

Liviu said...

It's easy - 6 and 4 (and 2 in 1400 vs 2 pm) are divisors of 12 so confusing them comes naturally; no odd number divides 12 though it is true that 5 and 7 are prime (and prime with 12 consequently) while 9 is not and eventually cycles to a multiple of 12 after 4 cycles, but that's far away to be less immediate

One wishes for a prime modulus clock (or equivalently angle degree measurement) and a prime modulus number base as lots of things would be much simpler, but i guess the 10 is ingrained from birth with fingers and toes and the 12 is way too ubiquitous for now to change

But the week is 7!

Liviu said...

oops, I meant no odd number beyond 3 but 1300 does not really bring 3 to mind, but 13 itself

Adam Roberts Project said...

Brilliant, Liviu.