This communication is largely founded on a paper entitled “Stresses in a Plate due to the presence of Cracks and Sharp Corners,” delivered by Professor C. E. Inglis, to the Institution of Naval Architects (1913). The importance of this contribution to the theory of fracture is recognized, and the results seem, among other things, to have a bearing on some geological problems. They may help, for instance, to explain the inception and development of sheet intrusions, under which class one may include ordinary vertical dykes (but not ring‐dykes), horizontal sills, and other hypabyssal bodies whose thickness bears only a very small proportion to their length.