[tz] Dealing with Pre-1970 Data

Lester Caine lester at lsces.co.uk
Sun Sep 1 21:43:26 UTC 2013

Guy Harris wrote:
>> Following on from that, indicating that some amendment from this base is in place and can be trusted would be useful.
> To what sort of amendments are you referring?  LMT is LMT, i.e. "1 hour for every 15 degrees of longitude from the prime meridian, and similar treatment of minutes and seconds of longitude".  There's nothing to amend there.

The amendments are the rest of the content of the tz database other than the 
base LMT time. Whether correct or otherwise. But based on Paul's last comment it 
would seem that it's time simply to start again gathering all of the facts again 
and assume nothing in the database is right? :)

The original question was 'do we need to start a second database with pre 1970 
history' my feeling currently that this should be undertaken simply because 
there is obviously no interest in managing the material within the current 
framework? Since nobody seems to have any confidence in what is being served up 
prior to 1970, then should any transitions be included at all? A single LMT 
based offset just to make the data stable and if we want historic information 
then basically we are already on our own anyway.

ALL I am trying to establish is if there is any demand to rectify the situation 
that you cut and pasted into you post on mass. What the current situation is has 
been quite clearly stated. That people do not want to LOOSE what history IS 
currently displayed has ALSO been established. So to MY mind, the next logical 
step is to re-assess the evidence and as a minimum give some level of confidence 
to that data. If that has to be outside of the existing database then so be it, 
and as a starting point, establishing how confident the LMT times are is 
essential. At least for the last century.

 From you quoting ...
> However, the database is not designed for and does not suffice for
> applications requiring accurate handling of all past times everywhere,
> as it would take far too much effort and guesswork to record all
> details of pre-1970 civil timekeeping.

Unfortunately that effort IS required for some applications of the data so when 
Paul says
> ... and for pre-1970 data most of the commentary will
> boil down to "see Shanks", which has been demonstrated
> to be unreliable when we've checked it.  There is little
> reason to trust that data.  Shanks gives no sources --
> zero -- for any of his data.

Then those of us who are looking to the past have to go back to basics and 
re-assess, something which I have been doing myself in the light of recent 
developments and now have the facts but no where to archive them :(

Does the existing TZ database want to make provision to handle the results if 
people are prepared to put in the work needed?

Lester Caine - G8HFL
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