A Priori Pathometry

affected individuals axis bell-shaped curve birth-rate Brownlee calculated centre of symmetry change of curvature considered continuous function death-rate deaths decreasing decreasing decreasing df/dt diminishes indefinitely dP/dt dx/dt element epidemics equal equation 12 equation 44 equations 50 equivariant example Explicit Operations f-curve function greater happening ceased Harrison & Sons Hence Hypometric Happening immigration and emigration immunity increasing increasing increasing Independent Happenings infectious diseases infectivity integrated equations integrating both sides L-cap limit London malaria measles natural increase negative non-affected number of affected number of individuals obtained occur ordinates period positive proportional curve Proportional Happening PUTNEY HEATH reaches remains constant reversion-element RONALD ROSS root Section VII SIR RONALD ROSS suppose tangential time-units lived total number total population ultimate value vanishes variation-elements whole population yields curves zero zymotic diseases