Published online by Cambridge University Press: 14 March 2018
Professor Becke's paper on skiodroms marks an important advance in our knowledge of the shadows, or isogyres, which are seen when sections of crystals are examined in convergent polarized light. The isogyres can also be advantageously studied in mineral grains, where the irregular shape disturbs the distribution of the interference colours, but has much less effect on the shadows due to the coincidence of directions of vibration in the crystal with those of one of the nicols.
Page 230 note 1 ‘Die Skiodromen. Ein Hilfsmittel bei der Ableitung der Interferenzbilder.’ Min. Petr. Mitt. (Tschermak), 1905, vol. xxiv, pp. 1-34 ; abstracted on p. 276 of this volume.
Page 230 note 2 Except for a brief allusion on p. 12.
Page 234 note 1 The use of the gypsum-plate in this way to determine the direction of the acute bisectrix in a section at right angles to the optic normal was first introduced by Professor Becke, Min. Pert. Mitt. (Tsehermak), 1897, vol. xvi, p. 181.
Page 234 note 2 Zeits. Kryst. Min, 1906, vol. xlii, p. 277; abstract in this vol., p. 281.