Tag: glass

Galileo Galilei’s Telescope Design Improvement Upon the Dutch Spyglass Design

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It had been known since the first spectacles were produced in the middle of the 13th century, that glass was capable of bending light, a property which no other known material of the period could achieve. The Dutch spyglass worked upon this very principal, arranging lenses with careful attention to detail to create a compounding magnification effect. If light hits a plano-convex (pronounced “play-noh”) lens, which is flat upon one side and convex upon the other, the same formation used for those who suffer from hyperopia, rays of light streaming inward are bent toward eachother, eventually meeting and converging at a specific triangular point. Right before this focal point, Galilei improved the original Dutch design by placing his second lens, an ocular lens which is plano-concave, meaning flat upon one side and concave upon the other, the same formation used for those who suffer from myopia. This secondary lens pushes the bent rays of converging light back out again so that they can hit the eye and provide a clear image. The eye focuses this light upon the retina so that the observer can view the image produced by the spyglass. The magnification power of a telescope depends upon the ratio between the focal lengths of the lenses, with these distances marked as F1 for the distance between the front of the spyglass and the plano-concave lens, and F2 from the plano-concave lens toward the back of the spyglass. The largest difficulty impeding Galilei was the grinding down process of his convex lens, in an attempt to make it as shallow as possible to maximize the length of the F1 partition, as the longer the distance is, the greater the magnification will be. Within a few weeks of developing this new technology, Galilei’s first telescope had a clear magnification of 8x, far exceeding the power of the original Dutch spyglass. On August 21, 1609, Galilei climbed a Venice bell tower to meet up with Venetian nobles and senators so that he could display his new technology. This new bleeding edge feat of engineering permitted Venetians to spot sailing ships 2 hours earlier than if they had used the naked eye. 3 days after the event, Galilei gifted his telescope to the Duke of Venice and was afforded a guaranteed job for life in exchange, with this salary equating to double his original income. With his finances secured, Galilei went on to develop and produce even more powerful telescopes

The First Mass Produced Items of the Ancient World

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The first mass produced pieces of artwork were the ancient Egyptians shabtis which were essentially miniature mummies that the ancient Egyptians believed had magical powers and were therefore buried with the dead. Shabtis were comprised of Egyptian faience which is a type of glass ceramic material made from sand. Egyptian faience is referred to as such in order to distinguish it from faience, which is a tin glazed pottery associated with Faenza, Italy. The idea of Egyptian faience was to replicate semiprecious stones like turquoise lapis lazuli from Afghanistan, which at the time was more expensive than gold. The recipe for Egyptian faience is 90% crushed silica, crushed fine natron salt to act as a flux, crushed limestone, and then the coloring with blue being the most popular, a color achieved through the use of pure copper oxide. Water was introduced to turn this composition from a granular mix into a dough like substance. Natron salt which is a type of baking soda, is the key ingredient to this recipe as it rises to the surface when baked and lowers the overall temperature at which sand melts and becomes glass. The statues are left to stand for 24 or more hours as this helps the salt grow on the surface through a chemical reaction process as oxygen within the ambient environment mixes with the ingredients inside the Egyptian faience

Ancient Stained Glass Manufacturing

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The manufacturing of stained glass is an ancient technology which dates back so far that the ancient Egyptians knew how to do it 2000 years before the birth of Jesus Christ. Medieval Europe inherited this form of technology but did not invent it as is common belief. Deep, rich blue glass was very difficult to make and therefore needed to be imported from southern Italy. The deep blues which the Chartres Cathedral in Chartres, France is so famous for can historically be traced through documentation to fragments coming from the Byzantine Empire as well as the Roman Empire. These imports were melted down and used to create new glass. Most colors and dyes came from the natural world in the forms of roots, berries, barks, leaves, minerals, and crushed insects, but the most prized colors were imported into Europe from the east, specifically India and China using Ottoman trade routes. The simple luck of geography made Venice, Italy an incredibly wealthy city as it acted as a nexus between the east and west. The blue hue referred to as “ultramarine” was the most expensive color to acquire and therefore it was almost always saved for depictions of the Virgin Mary, typically in her cloak or some other form of clothing, as Mary was depicted as the focal point of every painting she appeared within. Ultra Marine came from the mineral of lapis lazuli and when it was ground up into powder, some parts would inevitably become smaller than others which allowed these particles to reflect more light and provide a deeper, richer color to work with and appreciate. Vermillion Red was almost as precious as ultramarine, and has been used in Europe for hundreds of years in various illuminated manuscripts. Made from the mineral cinnabar, vermillion was adopted in places outside of Europe like meso-America for painting, India for bindi dots, and China to create lacquerware

Ancient Glass Manufacturing

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India has been making glass for over 3000 years. Pliny the Elder who was an Ancient Roman historian, states that the first glass was created near Syria around 5000 B.C. While this may be true, the earliest archaeological evidence of human made glass dates back to around 3500 B.C. in Eastern Mesopotamia and Egypt

The Dangers of Bright Light and Ultraviolet Light

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Contrary to popular belief, bright light cannot harm your eyes. Ultraviolet light can harm your eyes but ultraviolet cannot pass through glass, so staring at the sun or an atomic bomb which provides a ton of ultraviolet light is perfectly safe provided the observer is viewing the object through a glass panel (e.g. a car windshield). Richard Feynman used this knowledge to witness the first test of the atomic bomb in 1944, when no one else would dare to do so. Feynman viewed the detonation while sitting in his vehicle

How Tempered Glass is Manufactured

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Tempered glass is made from annealed glass which is regular glass, also referred to as “non-tempered” glass. Annealed glass is placed onto a roller table, taking it through a furnace which heats it 620 degrees Celsius, which is well above its transition temperature of 564 degrees Celsius in which it changes from a hard material into a soft rubber material. The glass is soon after rapidly cooled with forced air. The inner portion remains free to flow for a short time whilst the outer portion hardens quickly. An alternative chemical toughening process involves forcing a surface layer of glass at least 0.1 millimeters thick into compression by ion exchange of the sodium ions in the glass surface with potassium ions (which are 30% larger), by immersion of the glass into a bath of molten potassium nitrate. Chemical toughening results in increased toughness compared with thermal toughening and can be applied to glass objects of complex shapes

The Fallacy of Recycling Plastics

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Recycling is less of a reasonable solution to the plastics problems and more of a myth, shrouded in uncertainty towards the general public in terms of how effective it truly is. Polyethylene terephthalate plastic labeled as a “number 1” plastic and high-density polyethylene labeled as “number 2” are the main recyclable plastics. Most plastic isn’t recycled as is the case with glass or metal which can be melted down and used over and over again, but instead downcycled, in that they are used to create lower grade plastics used in things like park benches and plastic decking. Most plastics destined to be recycled which are produced in North America and Europe are shipped to China for processing. Recycling will not offset the plastic pollution being produced currently, as the rate of recycled plastic is approximately 30% meaning that for every plastic item we use, 70% of it is newly manufactured plastic, a value which will continue to grow for as long as human beings decide to continue to dump their wasted plastics in areas which are not publicly viewed (e.g. the ocean). Most plastic waste comes from plastic bags and plastic bottles. Collectively the world consumes 1,000,000 (1 million) plastic bags per minute and 28,300,000 (28.3 million) plastic bottles per minute. The plastics industry is the 3rd largest industry in the U.S., behind steel and vehicles, and is responsible for more than $400,000,000,000 ($400 billion) in product shipments per year. It is estimated that the average North American uses 300 – 700 plastic bags per year. By 2050, worldwide plastic production is projected to quadruple, reaching nearly 2,000,000,000,000 (2 trillion) lbs. per year