Small, lower cost models, perfect for demos, lectures, and classrooms.

Small, lower cost models, perfect for demos, lectures, and classrooms.

From Wikipedia,:

The bean machine, as drawn by Sir Francis Galton

The bean machine, also known as the quincunx or Galton box, is a device invented by Sir Francis Galton to demonstrate the central limit theorem, in particular that the normal distribution is approximate to the binomial distribution.

The machine consists of a vertical board with interleaved rows of pins. Balls are dropped from the top, and bounce left and right as they hit the pins. Eventually, they are collected into bins at the bottom. The height of ball columns in the bins approximates a bell curve.

Overlaying Pascal’s Triangle onto the pins shows the number of different paths that can be taken to get to each bin.

http://en.wikipedia.org/wiki/Galton_box

To help explain how a Galton Machine works, we wrote a computer simulation, shown below, which runs on either Mac OSX or Windows. It makes a great ‘interactive label’ for a real Galton Machine, or can be used by itself. If you would like to play with this software, you can download a free demo copy (not to be used for public display) by clicking the appropriate link:

Dance of Chance for MacOSX.zip

The first ‘Bean Machine’ we ever saw was this lovely and captivating design by Charles and Ray Eames, almost 50 years ago at the New York World’s Fair. Not every exhibit can give visitors life-long insight and inspiration --- but a Galton Machine can!

The Exhibit Guys would so love to make one for your museum!

For an in-depth discussion of the math underlying the Galton Machine, follow this link:

http://mathworld.wolfram.com/GaltonBoard.html