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    Re: GPS as a time authority
    From: Douglas Denny
    Date: 2009 Sep 16, 09:51 -0700

    Hello Brad,
    
    I agree the National Maritime Museum is still worth visiting as a lot of the 
    interesting exhibits are still there, and the ambience is still the same, 
    with the grand paintings of Naval battles, captains and the Great and the 
    Good. With lovely carpeted stairs; mahogany woodwork everywhere;  and plenty 
    of interesting  _things to see_ ...apart from the main attraction of Nelson's 
    bullet-holed jacket.
    
    Including for example, the wooden structural models (produced for acceptance 
    by the admiraly before they were built) of the sailing ships of the 18th and 
    19th century.  Anyone wanting to study the evolution and detail of admiralty 
    sailing ships can go into that display room and it is all there for close 
    examination: besides being an amazing set of ship models for the ordinary 
    disinterested visitor to marvel at their complexity and craftmanship.
    There is also still plenty of information detail presented with the artefacts 
    (though reduced from years ago as I remember it) so it is still worthy of a 
    visit to actually learn new interesting things.  That is what I go to museums 
    for!
    
    Contrast that with the 'Time Room' of the Observatory which has practically 
    nothing in the way of real information about time or navigation yet that is 
    exactly what the whole place was/is about.
    
    The very reason the Observatory was built was to promote the observing of the 
    heavens for finding of the 'much desired longitude' for navigation,  yet 
    there is little if anything to explain the detail of this, or how it 
    developed. In other words it fails in what I consider to the prime function 
    of a museum - to educate or inform, and it presently only attempts to 
    entertain on a very superficial level and that only at a level for children.
    
    I make no apology for the excoriating attack on the curators - they should 
    know better (and are paid well to know better) that their job is to maintain 
    the artefacts for posterity and to _display them_  for the public to _see_ 
    - and what is their job otherwise if it is not also to inform and educate?  
    
    Artefacts are quite useless objects when hidden away in dusty government 
    warehouses which is where they are now. They might as well be sold on EBay - 
    at least keen and interested people would own them and treasure them.  Fancy 
    one of the Greenwich Bygrave slide rules..?  Gary La Pook had to specially 
    ask to have them brought out for inspection - as you will not find one on 
    display in the science musum or the Observatory.
    --------------
    
    Mr. Huxtable mentions ovened quartz oscillators for frequency 
    standards/timekeeping. These were invented by Dr. Lois Essen of the National 
    Physical Laboratory in 1938, who produced the first quartz ring 
    electronically maintained oscillator,  which was the first time there was 
    something as good as or better than the Shortt pendulum clock of 1921.
    Quartz resonators are still used for high precision standards, only superceded 
    by Rubidium lamp standards and caesium based standards.  I have a Racal MA 
    259 double-ovened standard of the 1970's which has a short-term stability of 
    +/- one part in 10*9 for 24 hours  and long-term stability of +/- 2 parts in 
    10*10 over ten days.   All quartz crystals have a long-term unpredictable 
    drift to to 'crystal ageing', so they have to be checked against better 
    standards (Caesium or rubidium oscillators) at intervals).
    
    The 'Time Room' at the Greenwich observatory used to have one of the original 
    (if not THE original)- Essen ring quartz oscillator on display - which I note 
    was moved to the Science Museum when they decimated the 'Time room' and .... 
    now ....... gone.
    
    I could learn more about radio in Curry's than in the Science Museum's radio 
    section which is now practically non-existant and has been replaced with a 
    dynamic moving ART display in a huge room once occupied with interesting 
    items to see! (What is an _art_ display doing in a science museum one might 
    ask?).
    
    It must be just a sign of my getting old(er) and not appreciating the almost 
    indifferenct,casual superficial interest of people in things scientific of 
    this modern age perhaps?  I just get the strong impression these places were 
    so much better before when there were things to go and _see_ and read about.
    
    I have a collection of early Hughes bubble sextants and other artefacts which 
    was offered in the past to the RAF museum Hendon: they were not interested! 
    Didn't want to know apparently.  So the gentleman who owned them gave them to 
    me.
    I do not expect to donate them to any British museum in my will - because they 
    will stuff them into some dark corner of the warehouse in Wiltshire where 
    everything else is stored for the cockroaches to see.
    
    Douglas Denny.
    Chichester. England.
    
    
    ======================
    Original Post:-
    
    Hi Douglass
    
    I must say that I rather enjoyed my visits to the Greenwich Museum and the 
    National Maritime Museum down the hill.
    
    Harrison's chronometers were fascinating to watch.  I drove my wife absolutely 
    bonkers.  Contrary to Mr. Betts' opinion, I spent the better part of 2 hours 
    staring at the mechanisms, on each of my two visits to that room.  Would have 
    spent more time there but my wife mutinied.
    
    I found the NMM and the displays of navigational equipment, like the repeating 
    reflecting circles on the second floor, to be wonderful.  I would easily do 
    that again.
    
    I suppose I have pity on the poor curators.  Catering to the whims of the vast 
    majority of un-educated tourists, whilst disappointing the thirst of the 
    knowledgable.
    
    Best Regards
    Brad
    
    
    
    
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