Reading stone
A reading stone was an approximately hemispherical lens that was placed on top of text to magnify the letters so that people with presbyopia could read it more easily. Reading stones were among the earliest common uses of lenses. Reading stones were developed in the 8th century, following the development by Abbas Ibn Firnas of a process for converting sand into glass. Glass could be shaped and polished into stones used for viewing. Early reading stones were manufactured from rock crystal (quartz) or beryl as well as glass. The Visby lenses may have been reading stones.
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Reading stone
A reading stone was an approximately hemispherical lens that was placed on top of text to magnify the letters so that people with presbyopia could read it more easily. Reading stones were among the earliest common uses of lenses. Reading stones were developed in the 8th century, following the development by Abbas Ibn Firnas of a process for converting sand into glass. Glass could be shaped and polished into stones used for viewing. Early reading stones were manufactured from rock crystal (quartz) or beryl as well as glass. The Visby lenses may have been reading stones.
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A reading stone was an approxi ...... may have been reading stones.
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Ein Lesestein (auch Hellfeldlu ...... ch von Sehbehinderten genutzt.
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Una Piedra de Lectura era un o ...... el inventado en el siglo XVII.
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735,845,606
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comment
A reading stone was an approxi ...... may have been reading stones.
@en
Ein Lesestein (auch Hellfeldlu ...... ch von Sehbehinderten genutzt.
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Una Piedra de Lectura era un o ...... stal de roca y berilo pulidos.
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Lesestein (Optik)
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Piedra de Lectura
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Reading stone
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