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Please not that the Wikipedia page that is noted in this posting also said that the crown glass sheet was cut into smaller panes. The point made here is that as crown glass is very thin on the outer edge of the disk making it unstable just where it would be in contact with a frame. I have copied the Wiki entry for Crown Glass into this posting. Crown glass was an early type of window glass. In this process, glass was blow into a "crown" or hollow globe. This was then transferred from the blowpipe to a pontil and then flattened by reheating and spinning out the bowl-shaped piece of glass (bullion) into a flat disk by centrifugal force, up to 5 or 6 feet (1.5 to 1.8 metres) in diameter. The glass was then cut to the size required. The thinnest glass was in a band at the edge of the disk, with the glass becoming thicker and more opaque toward the center. Due to the distribution of the best glass, in order to fill large window spaces many small diamond shapes would be cut from the edge of the disk and these would be mounted into a lead lattice work and fitted in the window. Known as a bullseye, the thicker center area around the pontil mark was used for less expensive windows. Crown glass was one of the two most common processes for making window glass until the 19th century. The other was blown plate. The process was first perfected by French glassmakers in the 1320s, notably around Rouen, and was a trade secret. As a result, crown glass was not made in London until 1678. Crown glass is one of many types of hand-blown glass. Other methods include: broad sheet, blown plate, polished plate and cylinder blown sheet. These methods of manufacture lasted at least until the end of the 19th century. The early 20th century marks the move away from hand-blown to machine manufactured glass such as rolled plate, machine drawn cylinder sheet, flat drawn sheet, single and twin ground polished plate and float glass. George -----Original Message----- >From: Peter Meurer <petermeu...@online.de> >Sent: Nov 27, 2011 1:09 AM >To: Discussion group for map history <maphist@geo.uu.nl> >Subject: Re: [MapHist] Use of sheet glass > >This is a MapHist list message (when you hit 'reply' you're replying to the >whole list) >o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + > >My amateurish rummaging in WWW brought an astonishing knowledge to me. We >cannot exclude rather large panes of glass around 1550. >Try "crown glass (window)" in the English Wikipedia for the late medieval >products in Rouen. > >PHMeurer > >----- Original Message ----- >From: "Joaquim Alves Gaspar" <alvesgas...@netcabo.pt> >To: "'Discussion group for map history'" <maphist@geo.uu.nl> >Sent: Saturday, November 26, 2011 11:24 PM >Subject: RES: [MapHist] Use of sheet glass > > >This is a MapHist list message (when you hit 'reply' you're replying to the >whole list) >o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + > >Dear Vladimiro & all > >The expression "mapamundo em vidro grande" translates literally as >"mappamundi in large glass". However its meaning is somehow ambiguous in >Portuguese as it may also mean "a large mappamundi made of glass", "a large >mappamundi in(side) glass" or "a mappamundi in a large glass". Having >discarded the possibility of being a terrestrial globe or a map made of >glass, we are left with same sort of frame or protective case with glass. >For the reasons already explained, it is unlikely that a large sheet of >glass was used. If it were a traditional Ptolemaic world map (a printed map) >it was probably small. However it is not obvious for me that the word >"mappamundi" refers to one of them, as I suspect that it might apply, at the >time, to both the Ptolemaic world maps and the nautical planispheres. Also >remember that the Portuguese cartographers were skilled in making manuscript >nautical charts, not printed maps! > >Joaquim Gaspar > >-----Mensagem original----- >De: maphist-boun...@geo.uu.nl [mailto:maphist-boun...@geo.uu.nl] Em nome de >Vladimiro Valerio >Enviada em: sábado, 26 de Novembro de 2011 21:44 >Para: Discussion group for map history >Assunto: Re: [MapHist] Use of sheet glass > >This is a MapHist list message (when you hit 'reply' you're replying to the >whole list) >o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + > >Dear all, >after a great deal of replies and hints and suggestions, I still wonder: >what does "mapamundo em vidro grande" mean? > >>From the linguistic point of view might "em vidro grande" means "covered >with a glass" ("under a glass", em=under)? or the only likely meaning is >"made on glass" (em=on)? Is there any scholar of portuguese language among >us who may give such a reply? Or to whom we may ask? I do believe that we >have to know the recurrence of "em" in various texts and contexts of that >period. >This is a path parallel to the other: the availability of great format of >sheet of glass in that period. > >vladimiro > > > >Il giorno 26/nov/2011, alle ore 21.53, Joel Kovarsky ha scritto: > >> This is a MapHist list message (when you hit 'reply' you're replying to >the whole list) >> o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o >+ >> >> On 11/26/2011 10:32 AM, George Carhart wrote: >>> I do not think that a sheet of blown glass off the size suggested was >ever produced in the mid 16th century. >> >> I do not have the following book, but it might be of some relevance here: >> >> Glass: A World History by MacFarlane and Martin, 2002, U. Chicago Press: >http://www.press.uchicago.edu/ucp/books/book/chicago/G/bo3621371.html . >ISBN: 9780226500287. >> >> I was able to scan the index via Amazon, but could not quickly spot >entries dealing with glass used in framing works of art. The table of >contents is also online, and there are several entries pertaining to >glass blowing, but I do not know if anything as specific as George's remark >is indicated within the book. >> >> Joel Kovarsky >> _______________________________________________ >> MapHist: E-mail discussion group on the history of cartography >> hosted by the Faculty of Geosciences, University of Utrecht. >> The statements and opinions expressed in this message are those of >> the author and do not necessarily reflect those of the University of >> Utrecht. The University of Utrecht does not take any responsibility for >> the views of the author. >> List Information: http://www.maphist.nl >> >> Maphist mailing list >> Maphist@geo.uu.nl >> http://mailman.geo.uu.nl/mailman/listinfo/maphist > >_______________________________________________ >MapHist: E-mail discussion group on the history of cartography >hosted by the Faculty of Geosciences, University of Utrecht. >The statements and opinions expressed in this message are those of >the author and do not necessarily reflect those of the University of >Utrecht. The University of Utrecht does not take any responsibility for >the views of the author. >List Information: http://www.maphist.nl > >Maphist mailing list >Maphist@geo.uu.nl >http://mailman.geo.uu.nl/mailman/listinfo/maphist > > >_______________________________________________ >MapHist: E-mail discussion group on the history of cartography >hosted by the Faculty of Geosciences, University of Utrecht. >The statements and opinions expressed in this message are those of >the author and do not necessarily reflect those of the University of >Utrecht. The University of Utrecht does not take any responsibility for >the views of the author. >List Information: http://www.maphist.nl > >Maphist mailing list >Maphist@geo.uu.nl >http://mailman.geo.uu.nl/mailman/listinfo/maphist > >_______________________________________________ >MapHist: E-mail discussion group on the history of cartography >hosted by the Faculty of Geosciences, University of Utrecht. >The statements and opinions expressed in this message are those of >the author and do not necessarily reflect those of the University of >Utrecht. The University of Utrecht does not take any responsibility for >the views of the author. >List Information: http://www.maphist.nl > >Maphist mailing list >Maphist@geo.uu.nl >http://mailman.geo.uu.nl/mailman/listinfo/maphist Dr. phil. George S. Carhart Habilitand und Freiewissenschaftler für Geschichte der Kartographie Institute für Kartographie, Technische Universität Dresden -------- Allacher Str. 196 D-80997 München (+49)0171-7550798 ---- 7 Lafayette Str. Portland, ME 04101 USA (+1)207-775-1239 _______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the University of Utrecht. The University of Utrecht does not take any responsibility for the views of the author. List Information: http://www.maphist.nl Maphist mailing list Maphist@geo.uu.nl http://mailman.geo.uu.nl/mailman/listinfo/maphist
