# Spherical

**The Kiss Precise**

Four circles to the kissing come.

The smaller are the benter.

The bend is just the inverse of

The distance from the center.

Though their intrigue left Euclid dumb

There’s now no need for rule of thumb.

Since zero bend’s a dead straight line

And concave bends have minus sign,

The sum of the squares of all four bends

Is half the square of their sum.

**Sir Frederick Soddy (1936)**