In the image to the left, once the knobbed pin, G, is removed, the stem (or limb) turns around inside the collar, S. In this way the entire microscope can thereby be inverted, and as such can be used as a inverted or chemical microscope, as seen to the right.
In order to place the microscope in this configuration, first the knob G is removed. Secondly the instrument is inclined. The horizontal tube can be rotated and then the entire instrument can rotate around the collar, S. Then the instrument is made vertical again via the compass joint. The horizontal tube can now be rotated to face a convenient dirction or the entire microscope can be rotated as required.