{{Short description|Optical device}} {{For|the divination technique|Lithomancy}} [[File:2015-08 archeon reading stone.JPG|thumb|Reading stone in Archeon, a historical theme park]] A '''reading stone''' is an approximately hemispherical lens that can be placed over text to magnify the letters, making it easier for people with presbyopia to read.<ref>{{cite journal |last=Scholtz |first=Sibylle K. |year=2012 |title=From Reading Stones, Glasses and Contact Lenses to Intraocular Lenses |url=https://pubmed.ncbi.nlm.nih.gov/26591072/ |journal=Vesalius}}</ref> Reading stones were among the earliest common uses of lenses.<ref>{{cite web |title=The history of glasses |url=https://www.zeiss.com/vision-care/en/eye-health-and-care/understanding-vision/the-history-of-glasses.html |access-date=2026-04-27 |publisher=ZEISS}}</ref>
The invention of reading stones is often credited to Abbas ibn Firnas in the 9th century,<ref>{{cite book|title=The Limits of Resolution|author=Geoffrey de Villiers and E. Roy Pike|year=2016|page=1|isbn=9781498758123|publisher=CRC Press}}</ref> although the regular use of reading stones did not begin until around 1000 AD.<ref>{{cite journal|year=1986|volume=30|issue=5|last1=Rubin|first1=Melvin L.|title=Spectacles: Past, present, and future|doi=10.1016/0039-6257(86)90064-0|journal=Survey of Ophthalmology|pages=321–327 |pmid=3520911 }}</ref><ref>{{cite web |title=History of optics |url=https://en.wikipedia.org/wiki/History_of_optics |access-date=2026-04-27}}</ref><ref>{{cite book|isbn=978-3-642-42281-2|year=2011|page=[https://archive.org/details/opticalfluoresce00quer/page/n13 2]|last1=Quercioli|first1=Franco|editor=Alberto Diaspro|title=Optical Fluorescence Microscopy: From the Spectral to the Nano Dimension|url=https://archive.org/details/opticalfluoresce00quer|url-access=limited|publisher=Springer}}</ref> Early reading stones were made from rock crystal (quartz), beryl and glass, which could be shaped and polished into lenses used for magnification.<ref>{{cite web |title=History of the reading stones |url=https://light-microscope.net/en/history-of-the-light-microscopy/history-of-the-reading-stones/ |access-date=2026-04-27}}</ref> The Swedish Visby lenses, dating from the 11th or 12th century, may have been early reading stones.
The function of reading stones was replaced by spectacles from the late 13th century onwards, but modern versions are still in use.<ref>{{Cite web |title=The history of spectacles |url=https://www.college-optometrists.org/the-british-optical-association-museum/the-history-of-spectacles |access-date=2026-04-27 |website=www.college-optometrists.org |language=en}}</ref><ref>{{Cite web |last=Optical |first=Zenni |date=2023-10-09 |title=The History of Eyeglasses: From Invention to Today {{!}} Zenni Optical Blog |url=https://www.zennioptical.com/blog/history-eyeglasses/ |access-date=2026-04-27 |website=www.zennioptical.com |language=en-US}}</ref><ref>{{Cite web |title=Eyeglasses And Their Journey Through Time – Byron MN {{!}} Byron Eye Care |url=https://byroneyecare.com/2016/05/25/eyeglasses-and-their-journey-through-time/ |access-date=2026-04-27 |website=byroneyecare.com |language=en}}</ref> In their contemporary form, they can be found as rod-shaped magnifiers, flat on one side, that magnify a line of text at a time, or as large dome magnifiers which magnify a circular area of a page. Larger Fresnel lenses can be placed over an entire page. The modern versions are typically made of plastic.
==See also== * Dome magnifier
==References== {{Commons category|Reading stones}} <references/> *{{cite web |url=http://www.antiquespectacles.com/history/reading_stone.htm |title=A good illustration of a reading stone in use |publisher=Zeiss Optical Museum, Oberkochen |accessdate=2011-03-06 }}
Category:Magnifiers Category:Corrective lenses Category:Arab inventions