I think this is the answer: Until the Middle Ages the time was shown in a distribution of 12 hours between sunrise and sunset. Since the duration of one hour in that measuring system is different depending on the season this hours are named unequal hours. Sundials where showing these unequal hours. Later a day (day and night) was divided into 24 equal hours regardless of the seasons. The length of an equal hour was similar to that of an unequal hour during the equinoxes. Therefore the name of equal hours was also named equinoxiale hours. A sundial showing these equinoxial hours was named an equinoxial sundial. So all the sundials since the modification of unequal hours in equal hours. An equatorial sundial shows the time in a plane which is parallel to the equator plane. This can be on a flat surface or on a cylindrical band which is located in that plane as it is the case in an armirally sphere.
Willy Leenders Hasselt in Flanders (Belgium) Visit my website about the sundials in the province of Limburg (Flanders) with a section 'worth knowing about sundials' (mostly in Dutch): http://www.wijzerweb.be Op 14-feb-2012, om 15:49 heeft J. Tallman het volgende geschreven: > Hello, > > After posting a picture of a dial to the list which was shown in a horizontal > attitude instead of being on an angled base as it should have been, I have a > broader question to ask. > > What is the real difference between a dial described as “equinoctial” and one > described as “equatorial”, and why would one term be chosen over the other to > describe a sundial? > > > Best, > > Jim Tallman > www.artisanindustrials.com > [email protected] > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
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