Greetings fellow dialists' I hope this comment is not too late for the conversation.
Frans W. Maes wrote: What is puzzling me is the following. From 1977 on we (in the Netherlands) had DST from the last weekend in March to the last weekend in September. Loosely speaking: while solar declination was positive. In 1996, the European Union adopted the British rule, moving the end of DST to the last weekend of October. Without moving the start of DST to the last weekend of February. Why this assymmetry? Apparently another factor than day length got into play. A political gesture to keep GB in the EU? Or just the average temperature? Even then, WHY? R. H. van Gent replied: As far as I can tell it was a political decision. In 1980 most of the EC observed the same begin and end dates for the DST period, whereas the United Kingdom usually started about a week earlier and ended about a month later. In 1981 the UK partly harmonized its DST period with the EC by beginning on the same day as the other EC member states. But it was not until 1996 when the EC member states harmonized the end of the DST period with that of the UK. I do not know whether astronomers (or other scientists) were ever consulted in choosing the best dates for the DST period. If so, I do not know their names. My comment: Clock times of sunrise and sunset are not the same at the end of October and the end of February and are not symmetrical around the winter solstice. For example, on the Greenwich meridian at 52N sunrise at the end of October is near 0648 UT and sunset is 1638 but at the end of February sunrise is near 0649 and sunset is 1737. Most of the differences between the October and February sunsets is due to the equation of time. Leaving the start of DST until the end of March reduces this difference. So perhaps an astronomer was consulted after all, or even a sundialist. Frank, 55N 1W. -- Frank Evans
