[time-nuts] Information on the Danjon Astrolab

[Poul-Henning Kamp]

In message <7ntf7JA6qD2EFwuF at g8kbz.demon.co.uk>, Geoff Powell writes:

>IIRC, the Danjon astrolabe uses a mercury pool, and a semi-reflecting
>prism.

Hmm, but doesn't the local value of "horizontal" affect the precision
also ?

You would really need to know the direction of local gravity for
this to be any good...

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