First 3D stereoscope

We take it for granted that we see the world in 3D, perceiving depth by the brain interpreting differing images in each eye. It was British scientist and inventor Sir Charles Wheatstone who in 1838 first came up with the idea of presenting slightly different images to the two eyes using a device he called a "reflecting mirror stereoscope". In 1840 he was awarded the Royal Medal of the Royal Society for his explanation of binocular vision and first demonstration of the stereoscope, where he showed with this equipment that two differing images may be combined in the brain to produce 3D depth perception. This invention stimulated the mass production of stereo photography, which flourished alongside conventional photography. Stereo photography peaked at around the turn of the 20th century and went out of fashion as movies increased in popularity.