AND WORM SPIRAL GEARING AND WORM SPIRAL GEARING A TREATISE ON THE PRINCIPLES, DI- MENSIONS, CALCULATION AND.DESIGN OF SPIRAL AND WORM GEARING, TO- GETHER WITH CHAPTERS ON THE METHODS OF CUTTING THE TEETH IN THESE TYPES OF GEARS COMPILED AND EDITED BY ERIK OBERG, A.S.M.E. ASSOCIATE EDITOR or MACHINERY EDITOR OF MACHINERY'S HANDBOOK AUTHOR OF "HANDBOOK OF SMALL TOOLS," "SHOP ARITHMETIC FOR THE MACHINIST," "SOLUTION OF TRIANGLES," "STRENGTH OF MATERIALS," "ELEMENTARY ALGEBRA," ETC. FIRST EDITION FIFTH PRINTING NEW YORK THE INDUSTRIAL PRESS LONDON: THE MACHINERY PUBLISHING CO., LTD. IQ20 COPYRIGHT, 1914 BY THE INDUSTRIAL PRESS NEW YORK