The BASE is sturdy machined casting fitted with Leveling Screws a carries fixed collimator arm and a swinging Telescope arm. TELESCOPE & COLLIMATOR tubes are carried in sturdy machined pillars, which arc accurately adjusted to make the Axis of the telescope a collimator pass through the axis of the instrument. The axis can be adjusted with the help of an adjusting pin. ADJUSTMENTS to the collimator, telescope tubes are provided for setting their optical axis at right angles to the vertical axis of the spectrometer. Both the Telescope Collimator tubes are fitted with smooth rack a pinion adjustment. The SLIT of the collimator is from brass and the slit jaws are finished and ground with the utmost care and optically tested for accuracy of the edges. The two jaws are operated by the knurled ring and move symmetrically from the center and remain parallel at all openings. A sliding Shutter is provided to increase or decrease the length of the slit. PRISM TABLE with grating holder is provided with three leveling screws and is engraved with concentric lines to facilitate the correct location of the prism. It may be raised or lowered & rotated independently of the Verniers.