Some readers have asked How can you make such a dial?
I would love to hear from an author of such dials to hear how it is done
in less than a year of marking points.
How did they do it?
Computer software certainly makes it easier. The popular Zonwvlak,
ZW2000, has long had a reflection function and one could play with
choosing distance and angles until satisfied. I have managed to find
that more recently three programs have been modified or specifically
written to aid in design and construction of reflected dials.
On the web site of Riccardo Anselmi you can find Cartesius Mirror, see:
http://sundials.anselmi.vda.it/AWA_2_GenericDocumentDynamic.aspx?p1=Software&p2=Software%20realizzati&p3=Software
I have not tried it but it seems very numeric.
As mentioned previously, Gianni Ferrari's program, Reflsun, can be found
in the Compendium, March 2004. It also is seems very numeric although
special diagrams are employed.
My favorite is the new edition of Gian Casalegno’s freeware, Orologi
Solari. It was part of the digital bonus of the Compendium, December
2014. It is available on line at http://www.sundials.eu/indexENU.htm
Here is the note sent by the author,
The main new feature is the addition of reflection sundials to the hour
angle family of dials. As usual all
the features of OS are now available for this new type of dial: all
types of hour lines, simulation, lighting
conditions computation, true horizon computation and use etc. Moreover
to facilitate the placement of
the mirror, tools similar to those already provided by Gianni Ferrari
software (thanks Gianni) have been
added: calculation of the position of the light spot at desired time
instants, calculation of the orientation of
the mirror from one or more measurements of the coordinates of the light
spot.
An original feature that I think can be very useful is to change the
orientation of the mirror with the
mouse (left button + shift key pressed) and to see in real time on the
screen the changes in the hour lines
pattern. When combined with the ability to insert a correctly sized
photo of the wall behind the dial, this
tool allows you to easily find the optimum orientation of the mirror.
A tutorial specifically dedicated to the design and construction of
reflection sundials is available at the
address (http://www.sundials.eu/download/riflessioneENU.pdf)(See
digital bonus.) I
hope it can be helpful in order to learn all the new features of the
program. This new release also includes
the new tables by Gianni Ferrari (thanks again Gianni) containing the
mean values of the Equation of
Time and of the Sun Declination for years from 2014 to 2061.
Thank you Gian!
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