The collimator is set laterally on an appendix of the platform together with a total reflection prism that directs the beam coming from the collimator onto the inlet face of the plate with almost normal incidence; a lever with a spring, activated by a long threaded rod, allows the prism to rotate slightly to adjust its orientation with respect to the plate.
In the first of the two spectroscopes the eyepiece tube is missing and the plate is chipped. The second is perfectly functional and is in a good state of repair.