Pappus chain

Pappus's chain is a geometric construct that consists of an infinite sequence of circles, each of which is tangent to both a common line and the previous circle in the sequence. The chain is named after the ancient Greek mathematician Pappus of Alexandria, who is credited with studying such arrangements. In more detail, the construction starts with a given circle tangent to a line. The next circle in the chain is drawn such that it is tangent to both the line and the first circle.