Where this tool comes from
Galton’s board
Francis Galton, an English scientist, built this board in the 1870s to show how chance adds up. He described it in his book Natural Inheritance (1889) and called it a quincunx; “bean machine” is a later nickname.
One thing to hold: A board with rows of pins. Lead shot pours in at the top, bounces through the pins and lands in a row of slots.
Why it matters: Each ball goes left or right by chance, yet together the balls pile into the same hump-shaped curve every time. One run is lumpy; the shape shows up when many balls fall.