AT a public meeting organized by the Association of Scientific Workers, held at the Royal College of Science, London, on November 19, questions relating to “Defence and the Responsibilities of the Scientist” were discussed by a representative gathering of scientific workers. Prof. J. B. S. Haldane presided, and Prof. S. Chapman and Air Commodore L. E. 0. Charlton opened the discussion. Prof. Chapman denied the accusation that science is responsible for the horrors of war; dismissed the proposal that scientific workers should refuse to do war work as impracticable; urged them to join with the general public in order to take the necessary political action to stop the use of science for purposes of destruction, and suggested finally that the most suitable form of action would be the setting up of an international police force under the auspices of the League of Nations. Air Commodore Charlton showed how one of the principal technical achievements of our age, the aeroplane, has brought war to our doorstep, and has made the world population centres, such as London, the principal military objective in a future war. He presented quantitative evidence of the inadequacy of all known methods of defence, and urged scientific workers to devise something that would render the use of bombers impossible. In the subsequent discussion, attention was directed to the alternative policies advocated for avoiding war. The general consensus of opinion seemed to be in favour of some system of genuine collective security, and rejected both the isolationist and the pacifist solutions. J. D. Bernal reported the principal recommendations of the Science Section of the International Peace Conference held in Brussels last September. These included the proposal that scientific workers should apply scientific method to the study of war in all its aspects, to investigate the causes of war from the point of view of social and biological science, and to expose pseudo-scientific theories justifying war and racial superiority. It was finally proposed that a national commission representing all branches of science be set up to co-ordinate this work. These recommendations met with the warm support of the meeting.