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Re: Optical toy



John,
Lenticular plastics is used to generate apparent 3 dimensional
effects. They are as the name implies curved so that each eye sees a
different perspective of the same picture, i.e. there are two pictures but
both are view at the same time with different eyes.
I believe the cards in question used triangular shaped groves in
plastic that show one picture when tipped one way and another when viewed
from a different angle. There is a big version of this idea in the science
museum in Florence where Galileo's telescopes are kept. Unfortunately their
webb site does not show that device, just some of Galileo's instruments and
his middle finger.
The device in question is composed of two paintings that have been
cut in strips which in turn are glued to the sides of some triangular
shaped boards. When you look at it from one side you see one picture and
viewed from the other side shows the other picture.

Gary

At 11:49 AM 6/6/02 -0400, you wrote:
Tony Wayne wrote:
>
> I have a old mini baseball card (from cracker jack) where the pitcher
> switches positions when you tilt the card at different angles.
>
> (1)Does anyone know what these cards are called?
>
> (2) Does anyone know how they are made/work?

http://www.google.com/search?q=lenticular+sheets