Microlevel

a measuring instrument in the form of a striding level for high-precision determination of the intervisibility of points or the inclination of the reference planes of various machines. It consists of a mounting with an elevating screw and rollers for movement, an accurate cylindrical level, and a dial indicator. The mounting is supported on the plane by two hemi-spherical knobs whose separation (the base of the instrument) can be varied from 500 to 2,000 mm. One of the supporting knobs is movable and is connected to the indicator pin. In leveling, the instrument is positioned on the points to be checked, the bubble in the level is moved to the zero mark by means of the elevating screw, and a reading is taken on the indicator. The microlevel is then shifted by 180° and the reading repeated. The excess between the two points is equal to half the difference between the readings. The measurements are accurate to 5–10 microns.