Theodolite, WILD HEERBRUGG, T2 old type Theo, Leica

Description

Telescope magnification: 24 Scale: 400gon Image location: reversed image Multiplication constant: 100 Addition constant: 0 Sensitivity of the alidade level: 20" Direct reading: , 2cc Estimate to: 1cc The achromatic telescope has about 24x magnification, internal focusing and illumination. Right next to the eyepiece of the measuring telescope is a second view for reading the circle. It is carried out with short microscopes, which reflect two opposite points of the graduated circles together in order to eliminate any eccentricity. The circular reading is already partially digitized for building types from around 1975 (lower risk of degree and minute errors) and takes place through the coincidence of the opposite pitch circle lines. A plane plate micrometer is used for this fine reading, which is divided into angular seconds (arc seconds) and replaced the verniers that were widespread until about 1940. As for the reticle, the T2 has set the standard with combined single and double strokes and the two spacer threads. The addition constant for simple tachymetry with a vertical ruler is almost zero. The coarse and fine movements in direction and elevation angle are arranged in the form of four rotary knobs on the alidade and the telescope supports. This takes some getting used to initially; later competing products (e.g. the ThII from Zeiss or the DKM2-A from Kern-Aarau) have therefore switched to two concentric rotary knobs. The base has an optical plummet, lighting connections and the horizontal circle adjustment. The arrangement of the three foot screws and the tripod plate set the standard for almost all later instruments, also from other manufacturers.