The authors are under great obligation to all of their friends who have assisted them in this work, particularly to their collaborator, Mr. W. R. Pyle; also to Mr. J. R. Towne of East High School, Minneapolis, Mr. C. F. Dutton, of the West High School of Commerce, Cleveland, Mr. E. Waite Elder, of the Eastside High School, Denver, Mr. C. E. Harris, of the East High School, Rochester, N. Y., Mr. Walter L. Barnum and Mr. Robert E. Hughes, of the Evanston High School, Evanston, Ill., and Dr. George de Bothezat, aëronautical expert of the Advisory Commission for Aëronautics. R. A. MILLIKAN Definition and Measurement of Force. Composition and Reso- lution of Forces. Gravitation. Falling Bodies. Newton's Laws Definition and Measurement of Work. Work and the Pulley. Detection of Electric Currents. Chemical Effects. Magnetic Effects. Measurement of Currents. Electric Bell and Tele- PORTRAITS OF PHYSICISTS AND ILLUSTRATIONS OF RECENT ACHIEVEMENTS IN PHYSICS |