leveling-screw

Century Dictionary and Cyclopedia

1. n. In a mill, a screw in the hurst or frame on which a run of millstones is placed, used to give a vertical adjustment and bring it to an exact level. It acts against an iron plate set in a bedstone.
2. n. In a surveying or portable astronomical instrument, any one of the screws used for leveling the horizontal plate or that part of the instrument on which the horizontal angles are read off. In most English theodolites and leveling-instruments there are two pairs of leveling-screws; in French and German instruments usually only three screws.