glass to glasses

Glass to glassesGlass to glassesCyril W Kett Optometry Museum and ArchiveCyril W Kett Optometry Museum and Archive

Glass occurs naturallyGlass occurs naturally

It was not until 3500 BC that glass was It was not until 3500 BC that glass was manufactured by manmanufactured by man

4500 years later glass was used to make lenses 4500 years later glass was used to make lenses that were inserted in a frame to make spectaclesthat were inserted in a frame to make spectacles


Glass occurs naturally when quartz is heated to high Glass occurs naturally when quartz is heated to high temperatures by volcanic action or lightning strikes to temperatures by volcanic action or lightning strikes to vitrify silica (SiOvitrify silica (SiO22))

It was valued for making cutting tools and decorative It was valued for making cutting tools and decorative beadsbeads

Manufactured glass is made by heating sand. It was first Manufactured glass is made by heating sand. It was first made in either Mesopotamia or Egypt about 3500 BC made in either Mesopotamia or Egypt about 3500 BC when it was found that adding sodium carbonate when it was found that adding sodium carbonate (Na(Na22COCO33) reduced the temperature required for vitrification ) reduced the temperature required for vitrification below that which could be achieved by wood furnacesbelow that which could be achieved by wood furnaces


The Nimrud lens is the oldest extant The Nimrud lens is the oldest extant lens, nearly 3000 years old, unearthed lens, nearly 3000 years old, unearthed in the Assyrian palace of Nimrud in in the Assyrian palace of Nimrud in what is now Iraq what is now Iraq

750-710 BC, discovered 1853, 38 mm 750-710 BC, discovered 1853, 38 mm diameter, 23 mm thick, plano convex, rock diameter, 23 mm thick, plano convex, rock crystal, rough ground, +9 Dcrystal, rough ground, +9 D

Held by the British MuseumHeld by the British Museum

Reconstruction of the palace where the Nimrud lens was found


Reading stones were used from 1000 ADReading stones were used from 1000 AD

With powers of 30 to 40 D they provided With powers of 30 to 40 D they provided magnification but did not correct an out-of-magnification but did not correct an out-of-focus presbyopic eyefocus presbyopic eye

They developed from the glass covers used to They developed from the glass covers used to protect reliquaries from the 8th Cprotect reliquaries from the 8th C


The first eyeglasses were made in Italy The first eyeglasses were made in Italy about 1286about 1286Dominican friar Giordano da Pisa said in a sermon in Santa Maria Novella in Florence on February 23 1306:

"It is not yet twenty years since there was found the art of making eyeglasses, which make for good vision ... And it is so short a time that this new art, never before extant, was discovered ... I saw the one who first discovered and practiced it, and I talked to him.”

13th C


Did Salvino D’Amato degli Armati of Did Salvino D’Amato degli Armati of Florence invent eyeglasses?Florence invent eyeglasses?Florentine historian Domenico Manni (1690-1788) relates that there was a tombstone in the now demolished church of St Maria Maggiore

14th C

Here lies Salvino D’Amato degli Armati

of Florenceinventor of eyeglasses

May God forgive his sinAnno Domini 1317


Eyeglasses were depicted for the first Eyeglasses were depicted for the first time in a painting by Tomaso da time in a painting by Tomaso da Modena painted in Modena painted in 1352

The painting is part of a fresco in the The painting is part of a fresco in the chapter house of the monastery of San chapter house of the monastery of San Nicolo in Treviso, ItalyNicolo in Treviso, Italy

14th C


The oldest surviving eyeglasses date The oldest surviving eyeglasses date from the early 14th C from the early 14th C

They were found in the Wienhausen They were found in the Wienhausen monastery, near Hanover, Germany in monastery, near Hanover, Germany in 19531953

14th C


Early eyeglasses had lenses of poor Early eyeglasses had lenses of poor optical qualityoptical quality The lenses had striae, air bubbles The lenses had striae, air bubbles and were poorly surfaced with and were poorly surfaced with asphericity and astigmatism.asphericity and astigmatism.

Ronchi test of 14th C rivet Ronchi test of 14th C rivet glasses by Rolf Willach 2008glasses by Rolf Willach 2008

Read this book

14th C


The techniques of making spectacle lenses of The techniques of making spectacle lenses of good optical quality evolved over several good optical quality evolved over several centuriescenturies

The glass workers of Venice developed blown The glass workers of Venice developed blown glass lenses about 1300 - glass lenses about 1300 - vitreos ab ocularis ad vitreos ab ocularis ad legendumlegendum - “glasses for the eyes for reading” - “glasses for the eyes for reading” The spectacle makers of Nuremberg developed The spectacle makers of Nuremberg developed mould-grinding in the late 14th Cmould-grinding in the late 14th C

Read this bookIt is more about spectacle It is more about spectacle

lenses than telescopeslenses than telescopes

14th C


The Trig Lane rivet spectacles are the oldest found The Trig Lane rivet spectacles are the oldest found in the UK. They date from before 1440in the UK. They date from before 1440

They were found during excavations in Trig Lane They were found during excavations in Trig Lane London in 1974London in 1974

Replica of the Trig Lane spectacles

15th C


The printing press and a method of quickly The printing press and a method of quickly making movable type were invented by making movable type were invented by Johannes Gutenberg about about 1440

This led to the mass production of booksThis led to the mass production of books

By 1500, printing presses in Europe had By 1500, printing presses in Europe had produced more than 20 million volumes. produced more than 20 million volumes.

There was now a great deal to read and a new There was now a great deal to read and a new demand for eyeglassesdemand for eyeglasses

15th C


The Worshipful Company of Spectacle The Worshipful Company of Spectacle Makers of London was granted its Royal Makers of London was granted its Royal Charter by Charles I in Charter by Charles I in 1629

Spectacle makers had been regulated by Spectacle makers had been regulated by city ordinances and by guilds in Venice, city ordinances and by guilds in Venice, Nuremberg and in Holland for 200 years Nuremberg and in Holland for 200 years previouslypreviously

The London based Company of Spectacle The London based Company of Spectacle Makers would provide examinations and Makers would provide examinations and qualifications for sight-testing opticians 270 qualifications for sight-testing opticians 270 years later, in 1897years later, in 18971629

17th C

glass to glasses

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