Convex Glass
Information On The History Of Wearing Glasses
Glasses can be traced back in our history as far as the
thirteenth century. The first signs of glasses lenses were
found in elementary crystals or convex shaped glass that
have been found in archeological digs dating back several
thousand years. It is believed however that these shaped
"lenses" were not used for any eyesight correction of
glasses lenses, rather they were used most probably as
magnifiers. It wasn't until much later, likely the first
glasses as such were developed in the mid-thirteenth
century from convex lenses. The term lenses itself is most
likely derived from the latin for "bean" as the slightly
convex shapr of the bean resembles a basic lens for
spectacles.
The earliest lenses used in any sort of glasses known were
made of quartz crystals and could be used for correction of
vision as well as simply magnifying.
As their viability as glasses became more widely known and
so popular, the process to make the glasses lenses
developed first into spectacles made from hand blown glass
- and later (likely the very end of the thirteenth century)
into shaped glasses whereby molten glass was formed into a
convex mold and so defined a lens that could be used as
glasses or spectacles for correction.
It is also believed that some Roman Emperors had lenses
formed into a type of spectacles that were made of
emeralds, and so became what were probably the first
prescription sunglasses.
The real development of glasses as documented however was in
Italy and were produced by craftsmen who were used to making
jewelry and so able to incorporate small crystal lenses into
structure that could support them in front of the eyes
without having to be held.
Of course this made the earliest glasses extremely expensive
as they were handmade by artisans and used glass which was a
very expensive material in the 14th and 15th centuries. The
first actual documented wearer of glasses however was the
Bishop da Provena in the 13th century who had some simple
magnifying crystals connected to short handles and then
joined together so that they could be balanced on his
nose….and became at the same time the first example
of "pincenez".
There remains today some dispute about the origins of
glasses and spectacles, as there is some evidence that
Marco Polo encountered them when exploring the East and
landing in China in 1270 or 1271. There is further credit
give then by the Chinese themselves to the even earlier
development of glasses - or at least of a practical
corrective (non-magnifying) lens to Arabia as much as a
century earlier.
Despite this somewhat disputed provenance, there is no doubt
as to the popularity that glasses enjoyed as the manufacture
of them became less of an artisan skill and more of a
manufacturing process using glass and being predictive of
the lens curvature and so correction for myopia in
particular.
It is interesting to note that although there is good
documentary evidence of glasses being produced in some
fairly significant volume in the 16th century - it was not
until much later in the early part of the seventeenth
century that the physics of the lens was actually understood
and how the correction for myopia actually came about. This
discovery or explanation is credited to Johannes Kepler who
studied optics for several decades, eventually publishing
his work in 1604.
The Determination of the Necessity for Wearing Glasses
About the Author
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