gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1963.033.263.06 A Simple Single-Axis Rotation Apparatus Hartshorne N. H. M.C., Ph.D., M.Sc., F.R.M.S., F.R.I.C. Formerly of the School of Chemistry, University of Leeds1

Communicated by Prof. A. Stuart, MSc., F.R.M.S., F.G.S.

Present address: Ivy Farm, Waldron, Heathfield, East Sussex.

 12 1963 33 263 693 696 Copyright © 1963, The Mineralogical Society 1963 Summary

The apparatus enables a small crystal to be rotated through 360° about an axis parallel to the stage of a polarizing microscope, while immersed in a liquid of known refractive index. Angles of rotation are measured on a graduated drum to the nearest degree. The working distances separating the crystal from the objective and the condenser are sufficiently small for wide-angle interference figures to be obtained. The crystal is easily mounted and centred.