 Following the basic premises of Descartes, Christiaan Huygens between 1669 and 1690 designed a much more exact vortex model.This model was the first theory of gravitation which was worked out mathematically.He assumed that the aether particles are moving in every direction, but were thrown back at the outer borders of the vortex and this causes (as in the case of Descartes) a greater concentration of fine matter at the outer borders.