Theodolites
Beautiful,
detailed, functional and calibrated, theodolites are still used today for
ultra high precision optical alignment and measurement. Theodolites are
instruments for measuring both horizontal and vertical angles, as used in
triangulation networks. They consist of a telescope mounted movably within
two perpendicular axes, the horizontal or trunnion axis, and the vertical
axis. These are supposed to be mutually perpendicular; if not, have
horizontal axis error. Widely used in mapping surveying, a theodolite is mounted on a tripod by means of a forced centering plate or tribrach, containing three thumbscrews for rapid levelling. Before use, a theodolite must be placed precisely and vertically over the point to be measured, centering and its vertical axis aligned with local gravity levelling.
A theodolite has a telescope with diaphragm fitted in the center on a base. It has one round vernier scale fitted along the telescope in vertical position & another round vernier scale fitted below the telescope in horizontal position. Both the vernier scales have two built in magnifiers for reading on both faces & a bubble tube fitted on the top. Antique replicas of theodolite makes a great corporate gift, a navy award or a conversation piece.
