The Most Bizarre Medical Tools from Back in the Day

Optokinetic Drum

The optokinetic drum was used to see the reflex movements of the eyes and visual illusions. The man in the photo, Dr. G.H. Byford, is wearing contact lenses with a mini lamp cemented to them so they can accurately track the eye movements.


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The More You Know

  • The sun and moon appear to be the same size in the sky because of an astonishing coincidence: the moon is 400 times smaller but 400 times closer.
  • A blue whale's tongue weighs as much as an elephant.
  • Elephants comfort each other with chirps.
  • Water makes different pouring sounds depending on its temperature.
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