The modern sextant has a fixed vernier, graduated in one degree of arc, a Tangent Screw (Micrometer) which moves the index through one degree of arc for each revolution, and an Index Bar which clamps into a grooved arc beneath the Index Bar.
Isixhobo sangoku sinevernule ezinzileyo, esiphawulwe ngesiqingatha esinye sezazinge, isikrufu sehanjo nto (isixhobo sokulinganisa ezona zinto zincinane) esihambisa isalathiso kwinqanaba elinye lesazinge, lovukelo ngalunye, kwakunye nomgca wesalathiso othi ubambelele kumgca okrweliweyo wesazinge ngaphantsi komgca wesalathiso.