IN the fourth talk of his series, Mr. Cole approaches the great problem of population between 1750 and 1830, as it was set forth by the diverging opinions of Malthus and Godwin, respectively the pessimist and the optimist, as to whether England had not reached the stage of producing too many mouths to feed. This in its turn led to a growth in the scientific study of ' the dismal science' of economics, of which so much has been heard since the war.