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Sunstone

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Sunstone (medieval)
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This article is about the navigational tool. For the modern semi-precious gem Sunstone, see Sunstone (gem stone) or Wikipedia:Sunstone

The sunstone (sólarsteinn) is a navigational instrument used by medieval Scandinavians. In completely overcast skies, with the sun completely indistinguishable to the naked eye from the hazy white sky, the Sunstone allows more light to pass to an observer facing the sun. The user rotates, holding the stone near eye level, until the stone 'glows' when the position of the stone is most nearly between the sun and the users eyes. It requires practice and patience to determine the position of the sun in this way; by modern standards, this is a tenuous grasp on current location, but it was the difference between life and death for many a Nordic sailor. The mineral used to construct this crucial tool is fragile, and no surviving examples have been found, but it can be reconstructed (and has been scientifically tested as effective) with any adequate Wikipedia:Polarizer, such as can be formed with the minerals Cordierite or Iceland spar. Scientists hypothesized that the polarizing attributes of these minerals could increase light reception from the sun's position in the sky, and experiments to replicate this effect with modern polarizing lenses have yielded positive results.[1]

Sunstone is mentioned in several 13th–14th century written sources in Iceland, one of which describes its use to locate the sun in an overcast sky. Sunstones are also mentioned in the inventories of several churches and one monastery in 14th–15th century Iceland. No mention has yet been found of its use by seafarers in the Viking Age, but it seems likely that it was used by them, barring some unforeseen difficulty with using it on board ship.

The sunstone was 'rediscovered' as a navigational tool in the middle of the 20th Century. As early as 1949, working 'sky stones' were being used by aviators and the military.[2][3]

Sources

One medieval source in Iceland, "Rauðúlfs þáttr",[4][5] mentions the sunstone as a mineral by means of which the sun could be located in an overcast and snowy sky by holding it up and noting where additional light could be seen (hvar geislaði úr honum).[6] Sunstones are also listed in Hrafns saga Sveinbjarnarsonar (13th century) [7] and in church and monastic inventories (14th–15th century).[8] The sunstone texts of Hrafns saga Sveinbjarnarsonar were copied to all four versions of the medieval hagiography Guðmundar saga góða.[9]

The description in "Rauðúlfs þáttr" of the use of the sunstone is as follows:

Thorsteinn Vilhjalmsson translation:
The weather was thick and snowy as Sigurður had predicted. Then the king summoned Sigurður and Dagur (Rauðúlfur´s sons) to him. The king made people look out and they could nowhere see a clear sky. Then he asked Sigurður to tell where the sun was at that time. He gave a clear assertion. Then the king made them fetch the solar stone and held it up and saw where light radiated from the stone and thus directly verified Sigurður’ s prediction.[10]
In Icelandic:
"Veður var þykkt og drífanda sem Sigurður hafði sagt. Þá lét konungur kalla til sín Sigurð og Dag. Síðan lét konungur sjá út og sá hvergi himin skýlausan. Þá bað hann Sigurð segja hvar sól mundi þá komin. Hann kvað glöggt á. Þá lét konungur taka sólarstein og hélt upp og sá hann hvar geislaði úr steininum og markaði svo beint til sem Sigurður hafði sagt").[11]

Hrafns saga Sveinbjarnarsonar contains a mention of a sunstone.[12] alongside purely allegorical material associated with Hrafn’s slaying. Because so many otherwise mundane objects are used in a symbolic way in allegories, it is tempting to dismiss this as evidence, but allegories are a symbol of things known to the reader. The allegory is more or less fiction, and to convey its complicated message it depends at times on imaginary creations, but the better known to the listener the items in it are, the more functional they are to pass on the message of the allegory. In this way, a celestial vision with three cosmological knights, recalling the horsemen of the Apocalypse,[13] has allegorical allusions to the winter solstice and the four elements, as well as a sunstone; the two former would have been better known to contemporaries even than they are to modern day readers, and tend to confirm that the latter was, also. That they together constitute an omen of Hrafn’s death is both, less known to modern.

"Rauðúlfs þáttr", a medieval allegory of Saint Olav, gives clues to how the sunstone was used.[14] St. Olav used the sunstone to confirm the time reckoning skill of his host. He held the sunstone up against the snowy and completely overcast sky and noted where light came strongest from it. Use of the sunstone is described in sufficient detail to show that the idea of using a stone to find the sun's position in overcast conditions was commonplace.[15] The house belongs to the genre of of "abodes of the sun," which seemed widespread in medieval literature.[16]

A widespread tradition [17] has it that the virgin birth of Christ was compared with glass letting a ray of the sun through a sunstone.[18][19]


Sunstones for orientation and navigation?

Danish archaeologist Thorkild Ramskou posited that the sunstone could have been one of the minerals (cordierite or Iceland spar) that polarize light and by which the azimuth of the sun can be determined amid a partly overcast sky or when the sun is just below the horizon.[20][21] The principle is used by many animals[22] and was applied during polar flights before more advanced techniques became available. Ramskou’s theory that the sunstone could have aided navigation in the open sea in the Viking period is supported by experimental evidence,[23], but no extant records of the use of a sunstone for navigation exist in the medieval literature.

A polarizing crystal might have been useful, with repeated observations throughout the day, and fixed points of reference, as a sundial. High latitudes with extended hours of twilight, mountainous areas, partly overcast conditions, and known landmarks such as churches and monasteries would have have increased the value of such an object as an aid to keep track of the canonical hours.[24]

References

[1] [4] [5] [6] [7] [9] [10] [11] [13] [12] [14] [25] [26] [27] [16] [17] [18] [19] [8] [28] [15] [20] [21] [22] [23] [29] [24]

Citations

  1. ↑ 1.0 1.1 Ramskou, Thorkild. 1967. Solstenen. Skalk 2: 16–17.
  2. ↑ Google Books search for "Sky compass" The Aeroplane, Volume 87, Temple Press, 1954
  3. ↑ http://books.google.com/books?id=4wPtYmV2MUUC&pg=PA218&dq=polarizer+sunstone&hl=en&ei=cxYZTYCtDYKssAOXhLTiCg&sa=X&oi=book_result&ct=result&resnum=6&ved=0CEUQ6AEwBQ#v=onepage&q&f=false Google Books search for "Polarizer sunstone" Dawn Light: Dancing with Cranes and Other Ways to Start the Day by Diane Ackerman]
  4. ↑ 4.0 4.1 Turville-Petre, Joan E. (Trans.) (1947). The story of Rauð and his sons. Payne Memorial Series II. Viking Society for Northern Research.
  5. ↑ 5.0 5.1 Faulkes, Anthony. 1966. "Rauðúlfs þáttr: A study". Studia Islandica 25. Heimspekideild Háskóla Íslands og Bókaútgáfa Menningarsjóðs. Reykjavík. Template:ISSN
  6. ↑ 6.0 6.1 Sample, Ian."Crystals may have aided Viking sailors". Guardian (Manchester, UK) p. 8. 7 February 2007. Retrieved December 27, 2010. "Tests aboard a research vessel in the Arctic ocean found that certain crystals can be used to reveal the position of the sun, a trick that would have allowed early explorers to ascertain their position and navigate, even if the sky was obscured by cloud or fog."
  7. ↑ 7.0 7.1 Helgadóttir, Guðrún P (ed.). 1987. Hrafns Saga Sveinbjarnarsonar. Oxford: Clarendon Press. ISBN 0-19-811162-2.
  8. ↑ 8.0 8.1 Foote, Peter. G. 1956. Icelandic sólarsteinn and the medieval background. Arv. Tidskrift för Nordisk Folkminnesforskning 12: 26-40.
  9. ↑ 9.0 9.1 Karlsson, Stefán (ed.).1983. Guðmundar sögur biskups I: Ævi Guðmundar biskups, Guðmundar saga A. Editiones Arnamagnæanæ, Series B (6). København: C.A. Reitzels Forlag. ISBN 87-7421-387-3
  10. ↑ 10.0 10.1 Vilhjalmsson, Thorsteinn. 1997. "Time and Travel in Old Norse Society". Disputatio, (II): 89–114.
  11. ↑ 11.0 11.1 Johnsen and Helgason, Saga Óláfs, 670–1; Kristjánsdóttir et al., Heimskringla III, 23. cited in Vilhjalmsson, loc. cit.
  12. ↑ 12.0 12.1 Einarsson Á, (2010). "Sólarsteinninn: tæki eða tákn.," Gripla, 21, 281–97.
  13. ↑ 13.0 13.1 Helgadóttir, 1987.
  14. ↑ 14.0 14.1 Einarsson, Árni. 1997. "Saint Olaf’s dream house. A medieval cosmological allegory". Skáldskaparmál 4: 179–209, Stafaholt, Reykjavík. Template:issn
  15. ↑ 15.0 15.1 Einarsson, 2010.
  16. ↑ 16.0 16.1 Faulkes, 1966.
  17. ↑ 17.0 17.1 Breeze, Andrew. 1999. "The blessed virgin and the sunbeam through glass". Celtica 23: 19–29. Template:issn
  18. ↑ 18.0 18.1 Bragason, Úlfar 1988. The structure and meaning of Hrafns saga Sveinbjarnarsonar. Scandinavian Studies 60: 267–292. Template:issn
  19. ↑ 19.0 19.1 Einarsson, 2010.
  20. ↑ 20.0 20.1 Ramskou, Thorkild. 1967. Solstenen. Skalk 2: 16–17.
  21. ↑ 21.0 21.1 Ramskou, Thorkild. 1969. Solstenen â€“ Primitiv Navigation i Norden för Kompasset. Köbenhavn: Rhodos.
  22. ↑ 22.0 22.1 Horváth, Gábor and Dezsö Varjú. 2004. Polarized Light in Animal Vision: Polarization Patterns in Nature. Springer. ISBN 3-540-40457-0
  23. ↑ 23.0 23.1 Hegedüs, Ramón, Ã…kesson, Susanne; Wehner, Rüdiger and Horváth, Gábor. 2007. "Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies". Proc. R. Soc. A 463: 1081–1095. Template:issn.
  24. ↑ 24.0 24.1 Einarsson, 2010.
  25. ↑ Einarsson, Árni. 2001. The symbolic imagery of Hildegard of Bingen as a key to the allegorical Raudulfs thattr in Iceland. Erudiri Sapientia, Studien zum Mittelalter und zu seiner Rezeptionsgeschichte [Studies on the Middle Ages and its reception history]; II: 377–400. Template:issn
  26. ↑ Loescher, G. 1981. Rauðúlfs þáttr. Zeitschrift für deutsches Altertum und Deutsche Literatur (ZfDA) 110: 253-266. Template:issn
  27. ↑ Einarsson, 1997.
  28. ↑ Schnall, Uwe. 1975. Navigation der Wikinger. Nautische Probleme der Wikingerzeit im Spiegel der schriftlichen Quellen. Schriften des Deutschen Schiffahrtsmuseums. Band 6. Oldenburg og Hamburg.196
  29. ↑ Schnall, 1977.

External links

See also

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