Esther Bang
Feb 17, 2017 · 3 min read

Charles Wheatstone

The Binocular Discovery

The mystery of how humans perceive the world in three dimensions — with binocular vision through two eyes — has been a subject of scientific investigation since antiquity. In 1830, the English physicist, Charles Wheatstone, described the human ability to perceive depth due to the brain combining two slightly different images it receives when looking at something. Because the eyes are separated by a few inches, each eye is capable of seeing distinct aspects of scenes or objects, creating discrepant images. Thus, Wheatstone theorized that these discrepancies is what allows us to experience the world in three dimensions. In order to prove his theory, Charles Wheatstone created the “reflecting mirror stereoscope” in 1830.

(Figure 1 source: Zone, Ray. Stereoscopic Cinema & the Origins of 3-D Film, 1838–1952. Lexington, KY: U of Kentucky, 2007. Print.)

(Figure 2: “Stereoscope.” Wikipedia. Wikimedia Foundation, 15 Feb. 2017. Web. 16 Feb. 2017.)

The fundamental concept of binocular vision was not something new that Wheatstone stumbled on — it has been a subject of scientific speculation for many centuries. In Third century B.C., Euclid observed in his treatise on Optics that the right and left eyes see slightly different views of a sphere. And in second century A.D., the physician Galen, documented in his writing On The Use of the different Parts of the Human Body, a person standing near a column and observing first with the left eye, then with the right eye will see different aspects of the background behind the column. These developments led to Leonardo da Vinci (1452–1519) noting in his Trattato della Pittura (Art of Painting) that a point on a painting plane could never show relief in the same manner as a solid object.

“Painters often despair of being able to imitate Nature, from observing, that their pictures have not the same relief, nor the same life, as natural objects have in a looking-glass, though they both appear upon a plain surface…It is impossible that objects in painting should appear with the same relief as those in the looking-glass, unless we look at them with only one eye.”

Wheatstone first presented his stereoscope and his pioneering paper Contributions to the Physiology of Vision, Part the First: On Some Remarkable, and Hitherto Unobserved, Phenomena of Binocular Vision to the Royal Society of Great Britain in 1838. When viewed from above, The reflecting mirror stereoscope resembles a segmented capital M; two rectangular mirrors mounted at right angles, placed midway between two facing parallel drawings. As a viewer stands at the intersection and looks into the mirrors, he can see a virtual image where the object seems to have more volume than in either drawing alone. With his stereoscope and 12, 000 words treatise, Wheatstone was able to claim that when a single object is seen, two different pictures are projected on the retinas of the eyes.


  1. Zone, Ray. Stereoscopic Cinema & the Origins of 3-D Film, 1838–1952. Lexington, KY: U of Kentucky, 2007. Print.