THIS evening's talk in the series oh Tendencies in Industry Today deals with a subject that is being widely and keenly discussed now that women are everywhere establishing themselves in the economic sphere. Miss Lynda Grier has been Principal of Lady Margaret Hall , Oxford, since 1921 ; she is an ex-President of the Economics Section of the British Association, and she carried out an exhaustive investigation into the substitution of men by women in industry during the war, which was published by authority of the Association, in 1919 to 1921.