The 'river' of knowledge from the ancient world to medieval Europe flowed, in large part, through the Islamic world, which had appropriated much of the ancient learning. However, not all ancient learning arrived in the West in this way. For example, the important Archimedean treatises* On the Sphere and Cylinder *and *On the Measurement of the Circle*, were first introduced to the West through Latin translations from Arabic. But, such important Archimedean treatises as *On Spiral Lines, Quadrature of the Parabola*, and *On Conoids and Spheroids *were unknown in Arabic and became known to the West through Latin translations from the Greek by the Flemish Dominican William of Moerbecke in the latter half of the 13th century. -Len Berggren
On Wed, Feb 15, 2012 at 9:18 AM, nicolasever...@libero.it < nicolasever...@libero.it> wrote: > Dear Karlheinz, > > Certainly Hommilii or Hommel in his time was not an unknown scholar. In my > post I meant to say that his name is quite unknown today in the history of > sundials, unless someone proves to me that the name of Hommilii is often > cited in several books in the modern books. That the polar gnomon was > known since ancient times is good knowed. The Chinese used it because their > astronomy was the equatorial rather than azimuthal. However, if the > gnomonic of the Greeks and Romans was a great science and art, we can not > say the same of the Middle Ages, at least until 1400. What then is the > gnomonic medieval astronomy was transmitted to Europe by Arab astronomer > and not from the heritage of Hellenic science is well known. > > I think that the "river" of transmission from Greek-Roman to the medieval > era, was very restrict...although the monks made their great work of > saving... > > Nicola > > > ----Messaggio originale---- > Da: schalda...@aol.com > Data: 15/02/2012 17.19 > A: <nicolasever...@libero.it>, <sundial@uni-koeln.de> > Ogg: Re: R: Georg of Peuerbach > > > Dear Nicola et al. > Johannes Hommilius oder Johannes Hommel (See f. i. in the German > Wikipedia) was not an unknown German scholar. > For me it is also problematic to say that there was a break between the > Graeco-Roman and the medieval gnomonics. Maybe the river of transmission > became a brook, but the water still flew. And the polar gnomon was already > known in antiquity (though they had problems to use it for equinoctal > hours). Karlheinz > > > Hommilii from Memmingen > > > > > -----Ursprüngliche Mitteilung----- > Von: nicolaseverino <nicolasever...@libero.it> > An: rtbailey <rtbai...@telus.net>; Sundial List <sundial@uni-koeln.de> > Verschickt: Mi, 15 Feb 2012 8:43 am > Betreff: R: Georg of Peuerbach > > Hi Roger, > > I recently posted on my website a review of the book of Bartholomaeus > Scultetus: "Gnomonice, de Solariis...", 1572. Scultetus writes in his > introduction to some interesting historical information. One of these > quotes George Peurbach as the author of a book in which describes the methods > for drawing the first vertical wall sundials with the hours "ab occasu ", > the italic hours. Finally, the author dwells on the mysterious and > unknown works of gnomonic of an unknown professor of mathematics at > Leipzig, certain Johannis Hommilii from Memmingen in Bavaria, and author > of unknown "Gnomonicis meditationibus" and "Theoricae Gnomonicae", as > well as the "Lucubrationes and Inventiones" . > In any case Scultetus cites authors such important in the Gnomonica for the > Renaissance time: Johannes of Saxonia, Johannes of Gmunden, George > Peurbach, Johannes Regiomontanus and Iohannes Hommilii. > I thing that the european gnomonics, or the era of the vertical wall > sundials, starting with Robert Stikford (see the John Davis articles on BSS > Vol 23, decembre 2011) and follow the theorics of the mathematiciens like > George Peurbach and Johannes Regiomontanus. I pointed out severa manuscript > of the middle and the end of XV th century in which is possible to see > several sundials that look like the first european printed books. But is > only with the Orontius Finaeus, Apian, Munster, etc, that start the great > gnomonic of the first printed books. > The best > Nicola Severino > look the new february uptades ad > http://www.nicolaseverino.it > > > > > > > ----Messaggio originale---- > Da: rtbai...@telus.net > Data: 15/02/2012 6.43 > A: "Sundial List"<sundial@uni-koeln.de> > Ogg: Georg of Peuerbach > > I have been looking at the renaissance, the coming of age of science in > general and sundial science in particular in Europe. The dark ages were > just that, winter, a survival regime for intellectual thought and physical > existence. With the renaissance things changed, like blossoms in the spring > or the coming of age of people. I tend to view the world through a > specific window, the prism of sundials. This gives a distorted but colorful > view that avoids much of the noise in the general historical review and > provides a unique perspective. Everything I need to know was learned > through sundials > > Here my specific interest is the introduction of the polar gnomon. This > innovation gave us sundials that were independent of the seasons and could > be viewed from a distance, public instruments rather than private tools for > timekeepers and astronomers. On a planar sundial with a polar gnomon, > the shadows did not race off on tangents. Hour lines were constrained and > visible on a dial face. In the Moslem world, by the 14th century, there > was an a established science of astronomy, mathematics, instruments and > sundials. In 1371 Al-Shatir most likely created the first planar sundial > with a polar gnomon, almost as an aside, when he designed the complex > sundial at the Great Mosque in Damascus . He and his predecessors > established the mathematics and science that lead to this development. What > did we have at that time in Europe? Rudimentary fumbling in Germany, an > couple of experimental dials in Braunschweig, a rough rule from the > Monastery at Erfurt defining the angles for a sundial irrespective of > latitude and wall declination, a table of rudimentary design information > passed on by rote. In Europe when did real sundial science start? Perhaps > with Georg Peuerbach (1423-1461) in Austria. Google his name and follow > the links. He is well known and respected by Austrians an intellectual > force, the inventor of the ring and folding sundials, a skillful craftsman > producing astrolabes and sundials and the designer of some of the first > polar sundials in Europe. See http://www.regiomontanus.at/bild2_e.htm for > the first folding sundial, a dial with a portable polar gnomon. or > http://www.regiomontanus.at/bild2_e.htm the oldest sundial in Vienna. Was > he the spark of the Renaissance in sundial science? As one indication, > Peuerbach taught Regiomontanus. Knowledge advanced. > > Can you comment on my naive point of view or add more background on the > pioneering work of Georg Peuerbach? > > Regards, > Roger Bailey > Walking Shadow Designs > > > > > ---------------------------------------------------https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > -- J. L. Berggren Professor Emeritus Department of Mathematics Simon Fraser University 8888 University Dr. Burnaby, B.C. V5A 1S6 phone: 604-936-2268 fax: 604-936-2168 website: http://people.math.sfu.ca/~berggren/
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