—So we must distinguish between elliptical and ellipsoidal. Perhaps some of you gentlemen may be familiar with the works of Mr W. S. Gilbert. In one of his songs he speaks of the billiard sharp who is condemned to play:
On a cloth untrue
With a twisted cue
And elliptical billiard balls.
—He means a ball having the form of the ellipsoid of the principal axes of which I spoke a moment ago.