Hoop forces act in a latitudinal direction of a dome on the lateral faces of the voussoirs, and contribute significantly to the stability of domes. For a dome with uniform axisymmetric loading, hoop forces from adjacent slices are equal in magnitude and act in the same plane. On the representative lune plan view, the hoop forces act in a direction perpendicular to the lune lateral faces. The horizontal components of the hoop forces on each side of a voussoir are equal and opposite. The resultant of two complementing hoop forces is a net force toward or away from the dome's center. The magnitude of this resultant equals the horizontal distance between two consecutive x-points.