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The Weirdness of Zoetropes

We all know what a zoetrope is. One of those "cookie tins on a stick", with slots in the sides, that show a repeating cartoon of a second or so, from a strip of drawings. Dates from way back - 1860s, maybe earlier - and still found in some toy stores.

All true, but when we look closely at what a zoetrope is and does, things start to get a little weird - and despite such subjects as The Red Legged Ogre and his Dancing Poodle, the weirdness isn't just in the featured subjects.

First of all, there's quite a lot of high level math going on. English mathematician William George Horner dealt with that in the 1830s, when he proposed the "Daedaleum" - the first version of the device. It was a generation before an improved model was marketed, as the zoetrope. One (of many) pages of Horner's zoetropical mathematics looked like this:

But let's not go there. Instead, I'd like you to see a simple demonstration of an effect that's more than a bit counter-intuitive. Supposing we're viewing a strip with 13 pictures. How many moving characters will we be able to see at any one time? Well, half of them are on the section of strip that has the pictures facing away from us, so ... maybe six-and-a-half? Or a bit less - maybe six?

Well, courtesy of the Academy of Motion Picture Arts and Sciences, we can find out without having to buy or make a zoetrope.

Academy Zoetrope Demonstration

Count the moving figures. I'd say there are 10? So how does THAT work? (And no, you can't stop the video to count the number of skipping figures that appear at any one time, because that doesn't work. And the reason it doesn't work is..... errm, well...... I can't give you all the answers, or you'd all be experts too and where would that leave me?

Stephen Herbert

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