[time-nuts] Re: Brain Burp re Noon and the Sun!

[Poul-Henning Kamp]

--------
Michael Garvey writes:

> Take a look at the Dipleidoscope :
> (https://en.wikipedia.org/wiki/Dipleidoscope); they show up on eBay from
> time to time.  Accuracy is ~10 seconds.  They date from the mid-19th
> century.

Yes, marvelous instruments, full manual here:

	https://books.google.co.uk/books?id=9QlbAAAAQAAJ

But they are not "accurate", they are only "repeatable".

You set up the instrument, using either a known longitude ("from
the ordonance map") or an already calibrated chronometer, and
then it will tell you, with high repeatability when the sun
passes the instrument.

My experiment was trying to determine local noon without knowing
the longitude (or time) by measuring when the shadow was shortest.


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