gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1942.026.179.02 A Nomogram for the Law of Direction-Cosines Tomkeieff S. I. M.Sc., F.G.S. King's College, University of Durham, Newcastle-upon-Tyne. 12 1942 26 179 272 273 Copyright © 1942, The Mineralogical Society 1942