how do Moving Waterfall Pictures work

[Bramble-Stick]

Does anyone know ho these cheesey moving waterfall pictures work?

e.g

know that they contain a motor and I remember seeing something similar on lampshades when I was a kid, but never managed to get close up to take one apart ( I think that Boots would have objected)

Thanks!

Bramblestick

[Bruce]

buy such things?

I have only seen them in ethnic takeaways and restaurants, and mostly back in the 1970s.

[Bramble-Stick]

Absolutely agree - I wouldn't part with money for one. Just interested in how they work, so that I can see if I can build one. At least it will be a DIY taste fail - I'm of the Readers Digest Manual and Alternative London school of DIY so taste is compromised anyway :-)

Bramblestick

[Adam Aglionby]

Look up Moire pattern like

[Rod]

Which are (were?) also used for measuring cows. Seriously.

Can't remember the details but something like projecting two sets of fine lines onto a cow - the resulting moire fringes highlighted the shape of a cow.

[Bramble-Stick]

Excellent! Thanks for that - I'll have some fun playing around (already demonstrated it to myself using a folded piece of silk...), and hopefully the results won't be totally tasteless.

Bramblestick