 Eag acts on the wall's surface at one third of its height from the bottom and at an angle δ relative to a right angle at the wall.Eap acts at the same angle, but at one half the height.In 1948, Albert Caquot (1881–1976) and Jean Kerisel (1908–2005) developed an advanced theory that modified Muller-Breslau's equations to account for a non-planar rupture surface.