Note 27 — Chapter III · Investigation of Microscopic and Optical Characters of Minerals.
Reading edition
With the Seibert microscope, Fig. 2, the No. 0 eye-piece and the No. II objective will prove most satisfactory for the following tests. With the Fuess microscope use No. 4 objective. With an English microscope use an ordinary eye-piece and a 1″ or ¾″ objective.