Kevin Kendall developed the theory of cracks so as to apply it to a very wide range of problems of great industrial significance. Through a series of experiments, Kevin has shown that the thermodynamic theory of cracking can be used to explain and predict such varied phenomena as adhesion, some types of friction, colloidal behaviour and the internal structure of complex solids. Solutions have been obtained for the adhesion of elastic spheres, failure of lap joints, interfacial dislocations, delamination of a composite, failure in compression, crack arrest at an interface, rolling friction of cylinders, crushing of particles and the strength of porous solids, as well as the behaviour of powder compacts. He has also used theory synthetically to design polymer latex coatings and to devise new processes for making strong cements besides suggesting the optimum interfacial adhesion in composites. His work has also greatly illuminated a number of older problems such as Galileo’s argument on flaw statistics and Newton’s supposition on the attraction between spheres.