On the behavior of liquid drops on a solid surface. 1. The sliding of   drops on an inclined surface
  The idea of contact angle was generalized by using the principle of minimum total energy. The problems of the shape of the two-dimensional sessile drop and the drop on an inclined surface are considered. The differential equations describing the drop shapes are found in both cases. A case of good wetting is considered to determine the profiles of the sessile and inclined drops. The generalization of the boundary conditions for the contact angle hysteresis of the drop on an inclined surface is discussed. The limit of the inclination angle at which the drop begins to run down the inclined plane is found. The models of the drop detachment from the solid and the motion of liquid inside of the drop are discussed. This is not an original text. 
Y.I. Frenkel