In June 1838, the British scientist Charles Wheatstone published a paper describing a curious illusion he’d discovered. If you drew two pictures of something—say, a cube, or a tree—from two slightly different perspectives, and then viewed each one through a different eye, your brain would assemble them into a three-dimensional view. This was, he noted, precisely how our vision works; each eye sees a slightly different perspective. Wheatstone created a table-size device to demonstrate the effect, with a viewer that sent a unique image to each eye: the world’s first stereoscope.

A decade later, the scientist David Brewster refined the design, crafting a hand-held device you could raise to your eyes. Insert a card with stereo images —a “view”—and presto! A scene came alive. Better yet, the photograph had recently been invented, which meant Brewster’s stereoscope could display not just crude hand drawings, but vivid images captured from real life.

Once Brewster’s design hit the market, the stereoscope exploded in popularity. The London Stereoscopic Company sold affordable devices; its photographers fanned out across Europe to snap stereoscopic images. In 1856, the firm offered 10,000 views in its catalog, and within six years they’d grown to one million.

The world in a stereoscope seemed transcendent, hyper-real. “The first effect of looking at a good photograph through the stereoscope is a surprise such as no painting ever produced,” gushed Oliver Wendell Holmes, the American surgeon and author, in a 1859 Atlantic essay. “The mind feels its way into the very depths of the picture. The scraggy branches of a tree in the foreground run out at us as if they would scratch our eyes out.” Soon, Holmes amassed a collection of thousands of views. “Oh, infinite volumes of poems that I treasure in this small library of glass and pasteboard! I creep over the vast features of Rameses, on the face of his rockhewn Nubian temple; I scale the huge mountain-crystal that calls itself the Pyramid of Cheops.” He even gave this type of imagery a name: “stereograph,” from the Latin roots for “solid” and “writing.”

Holmes engineered a simplified stereoscope that could be made cheaply. He intentionally didn’t patent it, and this sparked an American stereography boom, as U.S. firms cranked out thousands of the gadgets. The device crossed all cultural and class boundaries: Intellectuals used it to ponder the mysteries of vision and mind, while kids merely goggled at the cool views. 

Stereoscopy began to transform science. Astronomers realized that if they took two pictures of the moon—shot months apart from each other—then it would be like viewing the moon using a face that was the size of a city: “Availing ourselves of the giant eyes of science,” as one observer wrote. (The technique indeed revealed new lunar features.) Artists used the device for inspiration. Charlie Chaplin was casting about unsuccessfully for an idea for his next film, when he peered at stereographs of the Yukon. “This was a wonderful theme,” he realized, and in a flash conceived the idea for his next hit film, The Gold Rush.

Eventually, the stereograph was killed off—by even newer, more bewitching media. Though the craze endured for over 60 years, by the 1910s, postcards had become the hot new photo item to share and collect. Then around the same time, radio arrived, and it permanently unseated the stereograph as social parlor-room entertainment. Stereo images never entirely vanished; 3-D has enjoyed a few short vogues in movies, and as the “View-Master” children’s toy in the ’60s.

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