THEODOLITE Russian patent published in 1997 - IPC

FIELD: geodetic instrument engineering, intended for geodetic, mine and engineer surveys. SUBSTANCE: theodolite has a through hole in the vertical axis providing for observation of marks in the area of the nadir point. For observation use is made either replacement of the set of hairs, or addition of the number of hairs of the main set, or observation of an additional set of hairs conjugate to the main one. Provision is made for application of an additional set of hairs on a vertical circle passing through the focal plane of the objective lens of the telescope. To lay the axis of sight on the zenith and nadir points, provision is made for a reversible level on the telescope. EFFECT: improved design. 5 cl, 4 dwg