When my mother proposed that we take a holiday together somewhere, and that I could choose the destination, I started by looking at the Geohashing Expeditions Map.
Where, I wondered, could I find a cluster of mostly-land graticules (“square” degree of latitude and longitude) in which nobody had ever logged a successful expedition?
I’ve been geohashing for ten years now and I’ve never yet scored a “Graticule Unlocked” achievement for being the first to reach any hashpoint in a given graticule.
Over the next week, if the fluctuations of the Dow Jones and the variable Irish weather allow, I’ll be changing that.
Maybe it’s just that my sabbatical is making me pay more attention then usual, but it feels like I’m getting very lucky with nearby geohashpoints lately. Tomorrow’s hashpoint in my
graticule might be achievable!
This is a good omen, perhaps, for next week. Next week my mother and I are going to hop over to the West coast of Ireland where there are several contiguous mostly-land graticules that
have never seen a successful expedition. We could be the first! 🤞
This weekend, while investigating a bug in some code that generates iCalendar (ICS) feeds, I learned about a weird quirk in the Republic of Ireland’s timezone. It’s such a strange thing (and has so little impact on
everyday life) that I imagine that even most Irish people don’t even know about it, but it’s important enough that it can easily introduce bugs into the way that computer calendars
communicate:
Most of Europe put their clocks forward in Summer, but the Republic of Ireland instead put their clocks backward in Winter.
If that sounds to you like the same thing said two different ways – or the set-up to a joke! – read on:
The timezones of Europe look pretty simple compared to some parts of the world, but the illustration of the British Isles hides an interesting eccentricity.
A Brief History of Time (in Ireland)
Spring forward, fall back… just a little bit back, though. Not too much.
After high-speed (rail) travel made mean solar timekeeping problematic, Great Britain in 1880 standardised on Greenwich Mean Time (UTC+0) as the time throughout the island, and Ireland
standardised on Dublin Mean Time (UTC-00:25:21). If you took a ferry from Liverpool to Dublin towards the end of the
19th century you’d have to put your watch back by about 25 minutes. With air travel not yet being a thing, countries didn’t yet feel the need to fixate on nice round offsets in the
region of one-hour (today, only a handful of regions retain UTC-offsets of half or quarter hours).
That’s all fine in peacetime, but by the First World War and especially following the Easter Rising, the British government decided that it was getting too tricky for their telegraph
operators (many of whom operated out of Ireland, which provided an important junction for transatlantic traffic) to be on a different time to London.
It’s widely believed that the world’s first “U UP? [STOP]” message never got a response as a direct result of Anglo-Irish timezone confusion.
So the Time (Ireland) Act 1916 was passed, putting Ireland on Greenwich Mean Time. Ireland put her clocks back by 35 minutes and synched-up with the rest of the British Isles.
And from then on, everything was simple and because nothing ever went wrong in Ireland as a result of the way it was governed by by Britain, nobody ever had to think about the question of
timezones on the island again.
Ah. Hmm.
“Those Irish people want to govern their own country, do they? After we so kindly shared our king with them? Right-ho: let’s set fire to their cities and see how
they feel then.”
Following Irish independence, the keeping of time carried on in much the same way for a long while, which will doubtless have been convenient for families spread across the Northern
Irish border. But then came the Second World War.
Summers in the 1940s saw Churchill introduce Double Summer Time which he believed
would give the UK more daylight, saving energy that might otherwise be used for lighting and increasing production of war materiel.
Ireland considered using the emergency powers they’d put in place to do the same, as a fuel saving measure… but ultimately didn’t. This was possibly
because aligning her time with Britain might be seen as undermining her neutrality, but was more likely because the government saw that such a measure wouldn’t actually have much impact
on fuel use (it certainly didn’t in Britain). Whatever the reason, though, Britain and Northern Ireland were again out-of-sync with one another until the war ended.
I like to imagine that the development of powerful computers by the folks at Bletchley Park was a result of needing to keep track of timezones across the British Isles.
From 1968 to 1971 Britain experimented with “British Standard Time” – putting the clocks forward in
Summer once, to UTC+1, and then leaving them there for three years. This worked pretty well except if you were Scottish in which case you’ll have found winter mornings to be even
gloomier than you were used to, which was already pretty gloomy. Conveniently: during much of this period Ireland was also on UTC+1, but in their case it was part of a
different experiment. Ireland were working on joining the European Economic Community, and aligning themselves with “Paris time” year-round was an unnecessary concession but an
interesting idea.
But here’s where the quirk appears: the Standard Time Act 1968, which made UTC+1 the “standard” timezone
for the Republic of Ireland, was not repealed and is still in effect. Ireland could have started over in 1971 with a new rule that made UTC+0 the standard and added a “Summer
Time” alternative during which the clocks are put forward… but instead the Standard Time (Amendment) Act
1971 left UTC+1 as Ireland’s standard timezone and added a “Winter Time” alternative during which the clocks are put back.
It all seems so simple until you actually think about it.
(For a deeper look at the legal history of time in the UK and Ireland, see this timeline. Certainly don’t get all your
history lessons from me.)
So what?
You might rightly be thinking: so what! Having a standard time of UTC+0 and going forward for the Summer (like the UK), is functionally-equivalent to having a standard time of UTC+1 and
going backwards in the Winter, like Ireland, right? It’s certainly true that, at any given moment, a clock in London and a clock in Dublin should show the same time. So why would
anybody care?
This code for Europe/Dublin, from the Perl module Data::ICal::TimeZone, is technically-incorrect
because it states that the winter time is the standard and daylight savings of +1 hour apply in the summer, rather than the opposite.
But declaring which is “standard” is important when you’re dealing with computers. If, for example, you run a volunteer rota management
system that supports a helpline charity that has branches in both the UK and Ireland, then it might really matter that the
computer systems involved know what each other mean when they talk about specific times.
The author of an iCalendar file can choose to embed timezone information to explain what, in that file, a particular timezone means. That timezone information might
say, for example, “When I say ‘Europe/Dublin’, I mean UTC+1, or UTC+0 in the winter.” Or it might say – like the code above! – “When I say ‘Europe/Dublin’, I mean UTC+0, or UTC+1 in the
summer.” Both of these declarations would be technically-valid and could be made to work, although only the first one would be strictly correct in accordance with the law.
But if you don’t include timezone information in your iCalendar file, you’re relying on the feed subscriber’s computer (e.g. their calendar software) to make a sensible
interpretation.. And that’s where you run into trouble. Because in cases like Ireland, for which the standard is one thing but is commonly-understood to be something different, there’s
a real risk that the way your system interprets and encodes time won’t necessarily be the same as the way somebody else’s does.
If I say I’ll meet you at 12:00 on 1 January, in Ireland, you rightly need to know whether I’m talking about 12:00 in Irish “standard” time (i.e. 11:00, because daylight savings are in
effect) or 12:00 in local-time-at-the-time-of-the-meeting (i.e. 12:00). Humans usually mean the latter because we think in terms of local time, but when your international computer
system needs to make sure that people are on a shift at the same time, but in different timezones, it needs to be very clear what exactly it means!
And when your daylight savings works “backwards” compared to everybody else’s… that’s sure to make a developer somewhere cry. And, possibly, blog about your weird legislation.
My dinner-party party piece for many years was to say, “Well, actually, I invented Baileys. You know, Baileys Irish Cream. I did that back in 1973.”
If one of the unfortunate listening group is a woman – and this is based on actual past experience – she is likely to respond something like this: “Oh-my-God. Baileys. My mother
absolutely adores it. Did you hear that, Jocasta? This man invented Baileys. It’s unreal. I don’t believe it. He must be terribly rich. Baileys Cream. Wow!”
And it’s not as if these rather posh people really adore Baileys. Or even hold it in the same esteem as, say, an obscure Islay single malt or a fine white burgundy from Meursault. Not
a bit of it. They might have respected it years ago but most people of legal drinking age regard Baileys as a bit naff. To my mind, they’d be very wrong…
