Thursday, 13 October 2011

A Line of Time at the 'Centre' of the World

Shepherd Gate Clock, 
Royal Obsevatory by 
Alvesgaspar Wikipedia 

October sees the end of British Summer Time, when the clocks go back, but it also marks the 127th anniversary of the introduction of Greenwich Mean Time by countries around the globe, which may not sound very exciting but is the reason time is calculated from the same base, no matter where in the world you are.

And that base is the Greenwich Meridian, zero degrees longitude, where East meets West at the centre of time throughout the world.  Its use as a universal marker for time was approved at an international conference held in 1884 ‘for the purpose of fixing a prime meridian and a universal day’.

Britain had unofficially standardised time in the 1840s when ‘railway time’ was introduced by train companies to ensure timetables were more accurate – prior to that time varied from town to town, which must have been confusing, especially where transport was concerned, but GMT was not legally adopted until 1880. However, for many years clocks in public places had two faces, or even two minute hands, to show local time and GMT.

 The Greenwich Meridian itself is an imaginary line (not a lion as I used to think in my schooldays) running from the North Pole through England, France, Spain, Algeria, Mali, Burkina Faso, Togo, Ghana and Antarctica to the South Pole. Known as early as 1738, its route is now indicated at night by a laser beam pointing north from the Royal Observatory at Greenwich, and was originally determined by the Airy Transit Circle, which sounds like some kind of magical atmospheric phenomenon but is actually a historic telescope.

If you are feeling energetic you can follow the line of the meridian from the point it reaches England at Sand le Mere, near Withernsea, in East Yorkshire, to its exit at Peacehaven, in Sussex - a trail using public footpaths has been established by The Long Distance Walkers’ Association.

Prime Meridian, Greenwich
by ChrisO Wikipedia Commons
These days Universal Time is atomic pieces, but is essentially the same as GMT, and the old terminology continues to be used by most people in Britain, including the BBC which still broadcasts hourly ‘pips’ for listeners.

Currently, of course, we are GMT plus one, since we are still in British Summer Time (set up in 1916 to provide an extra hour of daylight) but all that changes at 1am on Sunday, October 30, when the clocks go back and we revert to real time again.

If, like me, you can never remember what happens when, I find the following saying is helpful, even though it sounds American: Spring Forward, Fall Back.

By the way, most of the ‘information’ about the Greenwich Meridian in Dan Brown’s The Da Vinci Code is, apparently total rubbish, but there are masses of good websites – I found was helpful, even if I couldn’t understand all the detail.

1 comment:

  1. Chris - have you heard that there are plans to do away with GMT as the 'centre' of the world's time line?


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