The A B C of atoms

by Bertrand Russell

,

; this gives an ellipse in which the amount of flattening is a half, that is to say, the ellipse is two-thirds as high as it is broad, (c)

,

; this gives an ellipse in which the amount of flattening is two, that is to say, the ellipse is a third as high as it is broad.

In the fourth case,

, there are four possibilities; and so on. The breadth of the ellipse depends only upon