Note 22 — Chapter II · The Petrographical Microscope.[16]
Reading edition
In the Seibert microscope use objective No. 00 for the first general study of a rock section, No. II for general use and No. V for observations with convergent light. In the Fuess microscope use objective No. 4 for general use and No. 7 for convergent light tests. In the case of an English microscope a 1″ to ¾″ objective is used for general purposes and a ¼″ to ⅕″ for observations with convergent light.