Regarding Cone Aperture-Dials: I like tube-dials. (Cylindrical Circumference-Aperature Dials). They'd be my favorite south windowsill-dial, if they were easier to mount. That's their drawback for me. Their mounting requires orientation-exactitude in 3 axes. Making the dial is easy enough, but mounting it is a bit of work, especially since the mount has to be strong enough to support the tube. It gives me more appreciation for the more easily built and mounted Flat-Dials. No wonder they're the favorite stationary dials. They're my favorite stationary-dials too.
I considered an Aperture-Dial in the form of a cone. The inside is more easily visible. But the drawing of the hour-lines would be considerably more complicated than they'd be with a cylinder. To me that rules them out, because I like sundials whose construction can be easily explained. I wouldn't be inclined to set up a windosill sundial whose construction I couldn't explain to my girlfriend, Michael Ossipoff 20 Th (May 10th) 1414 UTC On Tue, May 7, 2019 at 1:57 PM Gian Casalegno <[email protected]> wrote: > Dear friends, > a new issue of the Italian magazine Orologi Solari is available for > download from the usual site http://www.orologisolari.eu/. > > Here is the list of articles together with a short abstract: > > 1. "A sundial made inside a cone" by Aironi John > We describe a sundial drawn inside a hollow cone, with a slit and a > gnomonic hole on a generatrix. Sunlight penetrating inside the cone through > a slit projects on the inner surface of the cone a light strip indicating > the time. The formulas for tracing hour lines and calendar lines are shown. > > 2. "Ancient hour circles on the sphere are not maximum circles. Clavio's > demonstration with AutocadLT." by Albéri Auber Paolo > Cristoforo Clavio, after a long discussion with his colleagues, finally > offered a demonstration that the maximum circle of ancient time relative to > two antisymmetric declination circles is different for each pair of chosen > declination circles, that is to say that the hour lines relative to the > ancient hour are not maximum circles. Here we propose a simplified > demonstration with images taken from AutocadLT geometric constructions. > > 3. "Small composite sundials" by Anselmi Riccardo > The author presents a model of a gnomonic hole dial made with an ice cream > container. In particular two specimens are shown and described declining > respectively to the south and to the west. > > 4. "The millstone of time" by Baggio Francesco > This article describes a horizontal mobile gnomon sundial already > manufactured and registered in Sundial Atlas with the code IT013689. > Project steps are explained and possible variants are proposed. > > 5. "An app for dialists… aspirant clockmakers" by Casalegno Gianpiero > The author describes an Android app that simulates some famous tower > clocks. The main features are described trying to underline the most > interesting aspects for a gnomonist. > > 6. "Definition of the orientation of a flat wall" by Caviglia Francesco > The definitions used by gnomonists for the parameters that specify the > orientation of a flat wall (gnomonic declination and inclination or slope) > are here discussed. Unambiguous and suitable operational definitions are > provided and some proposals are advanced. > > 7. "A reflection behind the other: the double-mirror" by Ferro Milone > Francesco > Double-reflection geographic sundials are realized by using > double-mirrors. The project is carried out with the help of a dynamic > software (Geogebra), a geographical one (GMT) and a gnomonic one (Orologi > Solari by Gianpiero Casalegno). Three computing examples and a project > image terminate the article. > > 8. "And before Foster ?" by Gunella Alessandro > The author wants to remind the reader that the use of "rulers" in the > construction of sundials, a method generally attributed to Samuel Foster, > was actually already proposed in the previous century. In particular an > instrument is shown as already described by Clavius and probably of > Germanic origin. > > 9. "The analemma and the Cathedral of Majorca" by Pol i Llompart Josep > Lluís, Ruiz-Aguilera Daniel > The authors describe the cathedral of Majorca and explain how they made > the photos of the solar analmma above the "cathedral of light". > > 10. "A Roman portable watch" by Quadri Ulisse > The author describes the use and the principle of operation of a portable > solar clock from the Roman era, kept at the Museum of the History of > Science in Oxford and of which he made a copy in brass and steel. > > A digital bonus can also be downloaded for additional reference material. > > Hope you will enjoy the reading, although in Italian only. > > Ciao. > Gian Casalegno > > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > Mail > priva di virus. www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > <#m_1923553163476235413_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > >
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