As I read, the gnomon by Berhard ('Berhadt-Walze') is a bit more
complicated than just the half analemma rotated. This, because the sun rays
are not orthogonal to the axis of the Berhardt-Walze and therefore it needs
some higher Maths. And as I remember the calculations show that there can
exist some days where reading correct mean time is not possible. As I
remember this happens the days near winter soltice.
Helmut Sonderegger
----- Original Message -----
From: "Thomas Steiner" <[EMAIL PROTECTED]>
To: "Sundial Mailing List" <[EMAIL PROTECTED]>
Sent: Wednesday, September 24, 2008 4:01 PM
Subject: Bernhardt's gnomons
> Dear all,
>
> I tried to collect information on Martin Bernhardt's special Gnomons
> which takes into account the equation of time in a equatorial sundial
> on a single scale to read off time, regardless of the date (almost -
> once a year the gnomon has to be changed).
> The idea is good and simple: just rotate half of the analemma (ok, a
> projection) around an axis. The original idea came from John Ryder
> Oliver (1834-1909) and Bernhardt lived from 1919 until 2000. It's
> incredible that this was discovered that late. Do you know any sources
> or other information on it? Do you know of any ideas/inventions that
> were close? What did Oliver exactly do? ...
>
> For the German speaking among you, I wrote major parts of this smal
> wikipedia article:
> http://de.wikipedia.org/wiki/Bernhardtsche_Walze
>
> Thanks for help on anything related to the subject...
> thomas
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