Thistreatiseisconcernedwiththestressesanddeformationofsolidbodiesincontactwitheachother,alongcurvedsurfaceswhichtouchinitiallyatapointoralongaline.Examplesarearailwaywheelandrail,orapairofgearwheelteeth.ProfessorJohnsonfirstreviewsthedevelopmentofthetheoryofcontactstressessince