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Glass In History
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Look at the Beginnings of Windshields
Early automotive windshields were dangerous, until the 'accidental' discovery of laminated glass by Edouard Benedictus. |
The use of plate glass in early windshields created the danger of the "glass necklace," a situation in which passengers could fly headlong into and through the windshield during a head-on collision. |
The earliest windshields, introduced by 1904, were folding affairs. When mud, rain, or other substances blocked his or her view forward, a driver could simply tip the top half down for an unobstructed view. (Goggles came in handy in those situations.) While the usefulness of windshields was clear to everybody, they posed a serious danger. Manufacturers quickly discovered that during an accident, their glass windshields could shatter, sending a shower of sharp shards into the vehicle. Glass windshields proved most hazardous during front-end collisions, when passengers could end up smashing headlong through the glass. Not surprisingly, when the first cars with glass on all four sides were introduced, many people were afraid to ride in them.
Early this century, two European scientists independently invented a solution to deadly windshields. While working in his lab, French scientist Edouard Benedictus accidentally knocked a flask to the floor. To his amazement, the glass did not break. Looking closer, he discovered that the chemical that had been inside the flask, nitrocellulose, had dried up, leaving an adhesive film that kept the numerous bits of fragmented glass from separating. Benedictus went on to develop a window consisting of two layers of plate glass held together by layer of cellulose.
Meanwhile, on the other side of the channel, British inventor John C. Wood had also been working with cellulose and had come up with his own method for cementing a layer of celluloid between two pieces of glass. Wood's shatter-resistant glass came to be produced under the brand-name of Triplex. Though it was first developed in 1905, Triplex was not brought to the U.S. until 1926. A year later, Ford began incorporating laminated glass into each of its automobiles.
In the 1950s, cars came off the line with side and rear windows of tempered glass. Tempered glass is made by placing one piece of glass into an atmospheric oven, which heats and hardens the glass. This treated glass can withstand forces of hundreds of pounds per square inch. When broken, it breaks into smooth beads that do not cut the skin, and unlike safety glass, rescuers can cut into it to reach victims trapped in a car.