dear Steve,
I did a search.
At first I realize that the dial has equiangle hours, so it seems to me,
if it is analemmatic sundial it means that the dial has the inclination
to get this condition (e.g. UK744 www.sundialatlas.net/atlas.php?sun=UK744).
This condition allows to turn the dial to adapt it to the time of
another longitude or to correct it for eot.
Than I thought that this condition is the same for an equinoctial dial
and may be it is not an analemmatic sundial, but an equinctial dial
adjustable for eot, so 'analemmatic' has this meaning.
The french page of wikepedia says the same of the english one: Cadran
analemmatiqueE. Ducretet
<https://fr.wikipedia.org/wiki/Eug%C3%A8ne_Ducretet>& L. Lejeune
(Paris), fin du XIX^e siècle. L'analemme montre « l'équation de la
fonction du temps » et permet la correction de ce que l'horloge lit.
I think something is lost, without the gnomon it is difficult to
understand it.
I found a book on internet, Catalogue des instruments de précision,
Lejuene, Ducretet (the two authors of the sundial and of others
scientific instruments), I found the book on sale on internet but also
the possibility to consult it online
(https://archive.org/details/cataloguedesins00parigoog). There is a
section starting at page 222, Cosmographie, where there are:
n. 1898 Chronomètre solaire de Fléchet fig 500
n. 1809 Méridien universel sur pied fig 501
Unfortunately this figures are not present (not scanned)
So I search for 'Chronomètre solaire de Fléchet' and I found some pages like
http://www.mhs.ox.ac.uk/collections/imu-search-page/record-details/?thumbnails=on&irn=2258&TitInventoryNo=34749
http://www.tessier-sarrou.com/html/fiche.jsp?id=5754802&np=3&lng=fr&npp=20&ordre=2&aff=1&r=
https://www.mhs.ox.ac.uk/collections/imu-search-page/record-details/?TitInventoryNo=42286&querytype=field&thumbnails=&irn=2257
and others. They are heliocronometers, that is equinoctial dial, with
turnable dial and with a tilting lens to get the Sun beam on the analemma.
I think this misunderstanding of the definition on Wiki depends on the
double meaning of 'analemmatic':
- with the analemma of eot
or
- azimuthal sundial with the gnomon adjustable for the declination of
the Sun.
ciao Fabio
Il 31/05/2019 07:30, Steve Lelievre ha scritto:
Hello everyone,
The English language Wikipedia page on analemmatic sundials has a
photo of a strange example at the National Polytechnic Museum, Sofia.
See https://en.wikipedia.org/wiki/Analemmatic_sundial and scroll down
to the last photo.
It's completely unlike any other analemmatic dial that I know of, so
I'm struggling to understand it. Which part is the gnomon? Which part
moves? Why do the hours run counterclockwise (Sofia is northern
hemisphere so presumably it was made for use there)? Why is there a
brace apparently welded to the dial face in front of the XII position?
What angle is the dial face at?
So many questions!
In short, how does it work ... can anyone enlighten me?
Thanks,
Steve
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Fabio Savian
fabio.sav...@nonvedolora.it
www.nonvedolora.eu
Paderno Dugnano, Milano, Italy
45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2)
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