Here is a video of something I believe Stan mentioned a while back - enjoy.
http://www.metacafe.com/watch/1295033/an......_solved/

Thanks for the link, Nir.

lawrens was the Café member who alerted us to the existence of this book.

When I first saw the Colin Ord book (via the link lawrens provided), I immediately thought Rufus Butler Seder had been ripped off.
To the best of my (very limited) knowledge,
Seder came up with the principle explained on the video.

Anyone know the history of the principle? Was it created by Seder?

In any event, the Ord book is very cool. I hope we see more such books
from Seder, Ord, and others.

One thing puzzling about Seder's book, Gallop! :
Why was the first animation used twice? Seems like a waste. It would
have been nice to have a different cover image.

Was at the book shops today and had the chance to feel the book with my hands.
the Gallop book is slightly different than the video. Each page has the special foil on top and it is glued to the opposite page, as you open to a page the foil is slightly dragged towards the left and this creates the illusion.
I would prefer the version shown in the video I linked to though.

seems like the foil is constructed in such a way that the ratio between the transparent slits and the black stripes is 1:(n-1) where n is the amount of different frames in the animation.

I believe this principle can be taken even further.
The foil need not necessarily be constructed from slits that go all the way from top to bottom. I believe that even a staggered slit pattern would be possible...
this might help conceal/scramble the original printed image.

another thought is maybe building a foil in a shape of a spiral.

now dear friends, how can this be used for a magical effect????
first guy who gets a neat idea will have is creation stolen by a slick magic dealer as a prize...

Stanalger wrote:

The principle is very old. I believe it was invented in ancient Greece, however, I'm not positive of that. I saw it in a book I read long ago.

The original implementation that I've seen in photos had a rotating cylindrical grating, with the drawing on a wide cylinder inside that had a diameter slightly smaller than the outer rotating grating.

I'll try to hunt down the source, and post what I find here.