Understanding: The Thaumatrope

The Thaumatrope is a small disk of card or paper that has a different drawing on each side, and two pieces of string attached to either side. When the strings were pulled on the disk would spin and create a sense of movement between the two images. This technique was credited to John Herschel, but was made popular as a toy by John Paris.

The Thaumatrope works by using persistence of vision, this is when the image that was seen previously stays in our field of vision for a few seconds after the image has actually been removed. By using this knowledge, people were able to create an image that flashed, quite rapidly, in front of them. However, persistence of vision is basically animation, as this is fundamentally how animation works and this was good knowledge for animation as a whole. 

Thaumotropes aren't a common toy today, however, I do remember making them as a child in primary school. Having said this, many people are unaware of what they are actually are and I don't see anyone using them as a toy or making them anymore. Despite this, the knowledge of persistence of vision is still widely used within animation and is one of the fundamentals to making animation.