AFH                 
<b><font face="Century Gothic">Got the time guv?</font></b><p>Yes, I've got the 
time, and the date!&nbsp; I'll deal with the time first..&nbsp; I am sure that 
many people are not aware of the advantages of a radio-controlled clock.&nbsp; I 
have three in my house.&nbsp; You may have seen the adverts claiming that they 
are accurate to an absurd degree; a second in fifteen&nbsp; million years.&nbsp; 
When I see grossly absurd advertisements, they usually act in the opposite 
direction to what they are intended to do.&nbsp; And I don't believe that I am 
much different to the average Brit.&nbsp; The advert <b>IS</b> absurd, but these 
clocks are still an excellent buy.&nbsp; The clocks keep time to better than a 
second <b>all the time they are working; </b>sufficient for most people.&nbsp; The method they 
use is to receive a radio signal from Rugby MSF at a very low radio frequency.&nbsp; 
This transmitter is the same one that calibration laboratories all over Britain 
use to lock their time and frequency counters to an atomic clock.&nbsp; It is 
the frequency of that atomic clock that has the accuracy that the advertisers 
quote, but even atomic clocks don't last 15 million years.&nbsp; The proper way 
of reporting the accuracy of a standard device like an atomic clock is to say 
that the uncertainty of measurement (UoM) is either a percentage, or so many 
parts per million (PPM).&nbsp; This equals one part in thirty-one million, five 
hundred and thirty-six thousand, times a million.&nbsp; So its much better than 
one second in a million million years.&nbsp; A truly stupendous accuracy.&nbsp; 
I won't attempt at putting the figure into scientific notation because this word 
processor cannot handle the layout of the figures.&nbsp; So, for all intents and 
purposes to a householder, it is perfect.&nbsp; But don't use the word &quot;perfect&quot; 
to a scientist, NOTHING is perfect.&nbsp; And science doesn't deal with 
religion.&nbsp; See my essays on page <a href="AAO.htm">AAO</a></p>
<p>&quot;Time&quot; is the physical parameter that can be measured to the greatest degree 
of precision.&nbsp; The actual physics are a bit abstruse, but atomic clocks are 
now a fairly common device.&nbsp; The National Physical Laboratory in Teddington 
has one and&nbsp; so have a number of other national laboratories.&nbsp; The 
average time of a number of atomic clocks worldwide&nbsp; is used as the 
International Standard.&nbsp; These clocks are more accurate than the rotation 
of the earth.&nbsp; Until these clocks were invented, mankind had to use the 
heavens as a time standard, but the boffins found that the earth speeded up and 
slowed down from time to time making the day a bit longer or a bit shorter, 
depending on the foibles of the planet..</p>
<p>The reason that I have three clocks is that I like to read the time in 
several locations in the house.&nbsp;Also, having three clocks allows me to see if 
one has gone wrong.&nbsp; When the battery runs down they behave erratically.&nbsp; 
And the battery doesn't last fifteen million years, depending on the type of 
cell, they last something over one year.&nbsp; When they go wrong, they are not 
just a little out of time, they are a lot out of time.&nbsp; But no different to 
a clockwork or ordinary battery clock.</p>
<p>Now to the date.&nbsp; I had a holiday in the USA in the 1980s after coming 
home from working in Syria.&nbsp; My wife presented a signed and dated 
traveller's cheque to a checkout girl in a supermarket,&nbsp; The girl said to 
my wife that she had put the wrong date on the cheque.&nbsp; My wife looked at 
the cheque again and said that she hadn't.&nbsp; Time for yours truly to 
interrupt.&nbsp; I explained to both of them that the UK and the USA write their 
dates in a different way.&nbsp; We use day-month-year in that order.&nbsp; The 
USA use month-day-year.&nbsp; Hence the confusion.&nbsp; But both countries are 
irrational as both countries use the same Arabic numeral system. (Don't ask my 
why, but the Arabs use Indian numerals.)&nbsp; </p>
<p>To be rational, we both should put the most-significant-digit first and the 
least-significant-digit last like we do for the writing of normal numbers.&nbsp; 
An example of the official international way of writing the date is 1995 12 05.&nbsp; 
This is the fifth of December 1995.&nbsp; If computer files are dated this way, 
the computer will put all the files in the correct date order.&nbsp; Using 
either the USA or UK layman's way will give the list in a strange order.</p>
<p>When the date and the time are written as a composite, as I have done above, 
it is referred to as the &quot;datetime&quot;.&nbsp; Various bodies from calibration labs 
to air traffic controllers use the &quot;datetime&quot; as part of their records.&nbsp; I 
am surprised that my Collins English dictionary doesn't list the word.&nbsp; I 
suppose a purist might hyphenate the two parts of the word.</p>