Re: astrolabes
Perhaps the book that is being thought of is "The Astrolabe, Some Notes on its History, Construction & Use" by R.S. Webster, Lake Bluff, 1974. It contains a card model of an Astolabe. I got a copy from Rogers Turner Books, Greenwich London. Luke Dave Bell wrote: > On Tue, 28 Apr 1998, RJS Crossley wrote: > > > Tarquin Publications of Stradbroke, Diss IP21 5JP, England, > > publish a splendid cut-out book of , by Gerald > > Jenkins and Magdalen Bear (ISBN 0 906212 59 6) - very cheap! I believe > > the same publisher offers an Astrolabe in the same format. > > > Richard Crossley. > > Dept. of Physics, University of York, York YO1 5DD, England. > > Cheap, indeed! $8.71 at www.books.com and appears to be in stock! > > Also by Jenkins/Tarquin, an entire series of cut-out and model books for > mathematical and astronomical education, all cheap... > > Haven't found anything by them on Astrolabes, though. > > Dave
Re: astrolabes
On Tue, 28 Apr 1998, RJS Crossley wrote: > Tarquin Publications of Stradbroke, Diss IP21 5JP, England, > publish a splendid cut-out book of , by Gerald > Jenkins and Magdalen Bear (ISBN 0 906212 59 6) - very cheap! I believe > the same publisher offers an Astrolabe in the same format. > Richard Crossley. > Dept. of Physics, University of York, York YO1 5DD, England. Cheap, indeed! $8.71 at www.books.com and appears to be in stock! Also by Jenkins/Tarquin, an entire series of cut-out and model books for mathematical and astronomical education, all cheap... Haven't found anything by them on Astrolabes, though. Dave
Re: astrolabes
Tarquin Publications of Stradbroke, Diss IP21 5JP, England, publish a splendid cut-out book of , by Gerald Jenkins and Magdalen Bear (ISBN 0 906212 59 6) - very cheap! I believe the same publisher offers an Astrolabe in the same format. At the other extreme is Humphrey Cole's astrolabe (and other mathematical instruments) which I had the good fortune to see on Saturday in a special exhibition at the British Museum (room 69a). Richard Crossley. Dept. of Physics, University of York, York YO1 5DD, England.
Re: Wall Declination
Dear Roger, Thank you for posting the directions for finding azimuth. I have found the "Dialist's Companion" equally valuable for some of the same purposes as you describe. Your explanation brings to mind how it would be possible to make an azimuthal dial for a window seal. The use of Zevonplot from Fer de Vries makes it very easy. Sincerely, Warren Thom Roger Bailey wrote: > Hello Fellow Dialists, > > > The solution was simple. Measure the azimuth of the sun through the > window! > The windows in well built modern houses (an oxymoron) are vertically > set in > the plane of the wall. The shadow of the window frame on a pad of > paper > held horizontally, with one edge pressed on the glass determines the > azimuth of the sun with respect to the plane of the window at that > instant. > All you need to do is mark the shadow line on the paper and the exact > time. > Take several readings, hours apart, for better accuracy and a check on > > measurements. To keep the orientation correct, I also note the rough > heading of north and add to the shadow line an arrow pointing to the > sun. > > Data reduction is still a problem. You have to correct for clock > error, > know the latitude, longitude, equation of time and declination of the > sun > and solve the usual spherical trigonometry equations to determine the > azimuth of the sun. This is greatly simplified using "The Dialist's > Companion" a program written by Terwilliger and Sawyer and published > by > NASS. Enter the appropriate data; the program solves for azimuth. From > that > calculated azimuth compared to the measured azimuth, the declination > of the > window (wall) is determined by simple geometry. > > The technique works very well. I have used it many times with > excellent > results. Generally the declination results agree to within half a > degree. > Errors are obvious as outliers. > >Cheers, > >Roger Bailey >Walking Shadow Designs >Canmore, Alberta, Canada >
Re: AW: Orthodox Easter (fwd)
Forwarded message: > Date: Mon, 27 Apr 1998 18:03:07 -0500 > Reply-To: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > Sender: History of Astronomy Discussion Group <[EMAIL PROTECTED]> > From: "David J. Ross" <[EMAIL PROTECTED]> > Subject: Re: AW: Orthodox Easter (fwd) > To: [EMAIL PROTECTED] > > Professor Lourie in St. Petersberg responded with the following remarks to the > cross post that I forwarded regarding the Easter computus, as it is known; it > seems his remarks and references may still be of interest. > > Rev. Dave Ross > > > From: >Basil Lourie <[EMAIL PROTECTED]> > Reply-To: >Christianity in Late Antiquity Discussion Group > <[EMAIL PROTECTED]> > To: >Multiple recipients of list ELENCHUS <[EMAIL PROTECTED]> > > > > > There are, in our days, three forms of the Christian Easter computus. > > Gregorian calendar is adopted not only by the Western Christians, but also > by a diocese of the Patriarchate of Constantinople -- the Autonomous Church > of Finland (since 1924 or perhaps 1926 -- sorry for this inexactitude). > > Julian calendar (completely or only as regard to the Easter computus) is > retained by all other Oriental communities (not only Chalcedonian, but also > others) with unique exception of the Church of Ethiopia. > > The Easter computus of the Ethiopian Church is even more archaic: it > corresponds to the Alexandrian computus before the middle of IIIth century. > On this see: O. Neugebauer, _Ethiopic Astronomy and Computus_ Wien 1979 > (Oesterreichische Akademie der Wiss., Philos.-hist. Kl., Sitzungsberichte, > Bd. 347; Voroeffenlichungen der Komission fuer Geschichte der Mathematik, > Naturwissenschaften und Medizin, H. 22). > > Also very useful are (I limite to the modern authors where the most part of > the > references to the earlier literature are available): > > O. Neugebauer. _Abu Shaker's "Chronography". A Treatise of the 13th Century > on Chronological, Calendrical and Astronomical Matters, written by a Christian > Arab, presented in Ethiopian_ Wien 1988 (Oesterreichische Akademie der Wiss., > Philos.-hist. Kl., Sitzungsberichte, Bd. 498). > > M. Richard. Le comput pascal par octa/et/eris, _Le Mus/eon_ 87 (1974); repr. > in > Idem, _Opera minora_ I, Leuven 1976, # 21, p. 307-339. > > There are also some works on the particular systems, such as the history of > the > Eastern computus in Georgian or in Armenian Churches or on the calendars of > the Jewish world of the 2nd Temple period (based, first of all, on the > Qumranic > data). > > Basil Lourie > > St.Petersburg Society for > Byzantine and Slavic Studies > > [EMAIL PROTECTED] > > RUSSIA 194356 > St.Petersburg > pr.Engelsa 135-132 > B.Lourie > Fax 7(812) 559 > > > > > Eugene F. Milone wrote: > > > Yes, I agree that the problem of Easter is solvable in the Gregorian context > > alone; that's why I thought the Julian Calendar issue was a 'red herring'. > > Sources indicate that only the Slavonic churches are on the 'Old (i.e., > > Julian) > > Calendar' at present. I have no information about when the other Orthodox > > churches moved to the 'New Calendar'. But the interesting thing is that > > all the Orthodox celebrate Easter on the same date -- unlike Christmas, > > which is rooted in the 13d difference between the Julian & Gregorian > > calendars. > > Cordially, > > - gene milone
