Nobert's test plate, Moller's diatom type slide, and modern microscopes

Nobert's Test Plate, as an instrument for trial, is admirably adapted for comparing the quality of object-glasses, supplied by different makers,and every microscopist who possesses a first-class instrument naturally desires to know what it is capable of doing; for when the power and quality of his lenses are known to him, he is convinced it would be only a waste of time to try them further.One of the most important tests that the properties of a microscope can be tried by is to clearly "resolve" the very fine lines of the frustules of the Diatomaceae. The value of minute Diatomaceae, is, in their surface markings, which are admirable test objects for the higher power of the microscope.