I contrived heretofore, a perspective by Reflexion.       —Sir Isaac Newton, c. 1668 The refracting telescope gave astronomers their first real glimpse of the heavens. Then, it began to frustrate them. At higher magnifications, the instrument’s glass lenses produced distorted images. Pioneering British scientist Isaac Newton solved the problem by using a %%metal%% mirror to %%gather%% light. He built his reflecting telescope in 1668. The more astronomers saw, the more they wanted to see.

They make glass. By day and night, the fires burn on … and bid the sand let in the light.      -Carl Sandburg, In Reckless Ecstasy , 1904. To see the unseeable: the quest is unending. But lenses and prisms are only as good as their glass. Optical-quality glass must be flawless. Even tiny flecks, streaks, or bubbles can cause distortion. With World War II approaching, optical glass was in great demand, and making it was a slow, crude process. The ingredients were put in ceramic pots, melted, stirred, then cooled. Only about 10 percent of the glass was usable.

I have heard a ray of the sun laugh and cough and sing!     -Alexander Graham Bell It was a bright idea: use sunlight to transmit the human voice. In 1880, American innovator Alexander Graham Bell tried it, using a thin, flexible mirror to reflect a light beam onto a distant receiver. His voice caused the mirror—and the reflected light—to vibrate. The receiver detected the light’s vibrations and turned them back into sound. Bell’s photophone worked, but it wasn’t practical. Rain, smoke—anything in the atmosphere—scattered the unprotected light signal.

The world began to realize that so far it had only toyed with glass. Now a brand new material was born.     -Walter Kioulehn, Odyssey of the 41 Glassmakers , 1959 By the mid-1800s, there were still only two kinds of optical glass: soda-lime crown glass and lead-containing flint glass. Opticians doubted they’d ever have more choices. Then a German glass chemist made a crucial discovery. In 1884, Otto Schott proved he could precisely alter the optical properties of glass by changing its chemical makeup. The variations in glass, it now seemed, could be endless.

Where the telescope ends, the microscope begins.    – Victor Hugo, Les Misérables , 1862 A glass lens. It’s nothing more than a curved piece of glass. So simple. So familiar. It’s changed the way we perceive the world. In 1608, when Dutch spectacle maker Hans Lippershey held up two lenses, one behind the other, he was surprised to see a close-up view of a distant steeple. He had discovered a powerful %%tool%%.

It was an idea that might have remained buried in scientific journals. Instead, it led to a device that gave modern telecommunications a much-needed boost.

After you see something work, then you realize that it’s not so complicated after all.      – J. Franklin Hyde It’s exquisitely pure and remarkably transparent. It expands and contracts very little with changes in temperature. It is the simplest of all glasses, yet for years it was nearly impossible to make: pure silica glass. In 1934, Corning organic chemist J. Franklin Hyde came up with a brilliant solution. Glass had always been made by melting dry mineral ingredients.

The most dangerous part of a sailing trip used to be returning to shore. Lighthouses were built to signal the safest route, but often the weak light from their lamps was not visible until too late. The large, thick lens that was supposed to project the light absorbed much of the signal.  Hollowing out the interior of the lens helped, but not enough. French physicist Augustin Fresnel knew that light rays spread out in all directions from their source.

Glass rods could transmit light, but could they transmit an image? A professor at a French agricultural college found himself faced with that question in the 1890s while he was tinkering with an early version of television.