Special Microscopes for Mineralogy & Petrography

Large model microscope for the study of rocks (fig 12). The construction of these instruments is based on this principle that, if the objective is rotated at the same time as the object, there cannot be any movement of the latter in the field of vision; we know that this is one of the conditions that a petrography microscope must meet, that is to say that it must keep any point of a preparation in coincidence with the crossed wires placed in the eyepiece, for the diferent orientation mesures required by these very interesting studies.

1892