The correct law for the composition of
forces, that forces add vectorially, had been discovered in the case of perpendicular
forces by Stevin-Simon (1548-1620) In 1586 A D , he analysed the principle of
geometric addition of forces in his treatise DeBeghinselen der Weeghconst
(“Principles of the Art of Weighing”), which caused a major breakthrough in the
development of mechanics