Dumpy Levels and Sextants

Abstract

Among the important survey instruments, optical type survey instruments, namely Dumpy Level, Sextants, Theodolites are used bv Civil Engineers, Surveyors, Mining Engineers, Rail and Road construction Engineers. The Dumpy Level is also called as screw precision level consisting of a Telescope internal focussing type, a spirit level, fully divided to facilitate setting and adjustment, levelling arrangements. The base plate is so designed to use with or without stand. usually the instrument is supplied complete with carrying case and tripod rigid leg. Wide application is made for measurements in underground and road construction for longitudinal and cross sections and for normal levelling purposes. Usually the instrument is approximately levelled in all meridians by means of the parallel screws or by ball joint in coniunction with a circular bubble. The final levelling for each sight immediately prior to readinz the staff is done by means of a micromete" \cre~l nrovided and zrsdiant can be set or measured. . One of the important features of the instrument is ~Xe range operating . and reading accuracy ~~; which the instrument is built. Sextants nre nsed for direction and measuring radiants.