making glass -- 5/25/21
Today's selection -- from The World in a Grain: The Story of Sand and How it Transformed Civilization by Vince Beiser. The Romans, and then the Venetians, took glassmaking to new heights:
"The Romans, as usual, took the technology to the next level. They made great advances in understanding how to use flux, to the point where they were able to manufacture glass in relatively large quantities and export it all over the empire. They figured out that adding manganese oxide helped clarify the glass, which led to a new invention: semitransparent windows. And they refined techniques of glass blowing that produced the most delicate wineglasses the world had yet seen.
"Glass caught on [quickly]. Glasses so clear they let tipplers see the color of their wine came into permanent fashion across Europe. Windows that let in light but kept out rain and cold were a tremendous quality-of-life boost for people living in more northerly, inclement climates (at least those who could afford them). Artisans mastered the process of coloring glass panes and created the beautiful stained-glass windows that still dazzle visitors at the cathedrals of Chartres, York Minster, and many others.
"Glassmaking developed into such a profitable art in Venice that in 1291 the city-state's rulers ordered all of the city's glassmakers to move to the island of Murano. There they were treated like aristocrats -- but not allowed to leave, lest they take their coveted craft secrets to rival nations. The sand for the Venetians' famous tableware and decorative items was an exceptionally pure type they brought in from the Ticino River, which flows out of the Alps past Milan.
"Today's Venetian artisans get their sand from France's Fontainebleau region, which is upward of 98 percent pure silica. (Corning, an American company that is one of the world's largest producers of glass and ceramics, also operates the world's largest ophthalmic glass production center in Fontainebleau.) Around the same time as the establishment of the artisan colony on Murano, the area around Valdelsa, in Tuscany, emerged as another important European glassmaking center. Glassmakers used the abundant local forests for fuel to melt sands from the Arno River and the beaches near Pisa. Unlike their Venetian counterparts, these artisans were free to emigrate, which many of them eventually did, spreading the glass trade across Europe. The Valdelsa region still provides some 15 percent of the world's leaded glass crystal.
"In the fifteenth century, Angelo Barovier, one of the Murano artisans and scion of a family of glassmakers, set about handpicking an elite selection of the purest sands he could find. He processed them carefully, and in time developed crystallo, the first truly colorless, transparent glass. This turned out to be a historic breakthrough.
"Transparent glass not only made for much better windows; it also made possible high-quality lenses, those unassuming little disks that have essentially endowed us with superpowers. The lenses of microscopes and telescopes enable us to see pieces of the universe we didn't even know existed, objects so tiny or so distant that our naked eyes could never perceive them. These innovations underpinned the scientific revolution.
"Telescopes and microscopes were preceded by simpler magnifying lenses in the form of eyeglasses, another tremendously important augmenter of human perception. 'The invention of spectacles increased the intellectual life of professional workers by fifteen years or more,' write Macfarlane and Martin. Eyeglasses likely abetted the surge of knowledge in Europe from the fourteenth century on. 'Much of the later work of great writers such as Petrarch would not have been completed without spectacles. The active life of skilled craftsmen, often engaged in very detailed close work, was also almost doubled,' Macfarlane and Martin maintain. The ability to read into one's old age became even more important once the printing press came into widespread use from the middle of the fifteenth century.
"It's not clear who invented the first telescope. Amid growing demand for eyeglasses, many people around Europe were experimenting with lenses and mirrors by the late 1500s. The first unambiguous record is from 1608, when an anonymous young spectacle-maker from the Dutch town of Middelburg offered an invention to the commander of the Dutch army: a tube containing two glass lenses, 'by means of which all things at a very great distance can be seen as if they were nearby.' The army brass immediately recognized the device's military potential. Within weeks at least three other Dutch inventors had applied for government patents on telescopes; none were granted, as so many people obviously knew the secret to making them. It's no wonder there was so much optical experimentation in the Netherlands: Holland boasted a sophisticated glass industry, of which Middelburg was an important center, thanks in part to the local abundance of high-quality river sands.
"Telescopes-powerful tools for navigators, military commanders, and even artists painting landscapes-spread at an astonishing speed. By 1609 small spyglasses were being sold in shops in France, Germany, England, and Italy. That spring, an Italian scientist named Galileo Galilei heard about them and began making his own. Rapidly improving prototype after prototype, he soon had a device capable of magnifying images twentyfold. Staring up at the night sky through his creation, Galileo was able to perceive truths about the cosmos that changed history. Among many other discoveries, he determined that the earth revolves around the sun, not the other way around -- a heretical notion at the time, one that got him placed under house arrest for much of his later life. Sand showed us our real position in the universe -- our planet is just one speck among billions."