GB402027A - Compass theodolite - Google Patents

Abstract

402,027. Theodolites. VERKAUFS-AKT.- GES. H. WILDS GEODATISCHE INSTRUMENTE, Heerbrugg, Switzerland. July 29, 1933, No. 21400. Convention date, Aug. 5, 1932. [Class 97 (ii).] The azimuth reading of a theodolite is obtained by reflecting into a single eyepiece diametrically opposite portions of the scale on a pivoted, graduated disc, which is fixed to a magnet and may be lifted from its pivot when desired. In the form shown the telescope 1 rotates about a horizontal axis 2 in a frame 3 rotatable about the vertical axis 4 on a base 5, a fine adjustment device 7 and clamp 8 being provided. Part of the frame 3 forms a casing 9 in which a graduated disc 10 fixed to a magnet 14 pivots on a pin 12 supported in the base 5 by the pillar 15 and foot plate 16. The disc 10 may be clamped against the inturned edge 17<1> of a basket 17, fitted to the base 5, by a lifting plate 19 which is mounted to slide up and down the pillar 15 and may be raised to the clamping position against the action of the spring 26 by a bell crank lever 23 operated by a screw 22. Diametrically opposite portions of the scale on the disc 10 are illuminated through windows 27 and 28 and reflected by prisms 29, 31 and 30, 32 respectively into prism 33 and eyepiece 34. The graduation marks of the two images may be brought into coincidence by rotation of a parallel sided glass plate 35 which is arranged between the prisms 29, 30 and 31, 32 and fixed to a pointer 39 moving over a scale 40. The latter gives the correction to be applied to the mean of the two graduations brought into coincidence. The eyepiece 34 may be arranged in the plane of revolution of the telescope 1 and may be tiltable together with the prism 33 about a horizontal axis.