GB313960A - Improvements in repeating theodolites - Google Patents

Abstract

313,960. Zeiss, C., [Firm of]. June 20, 1928, [Convention date]. Theodolites. - In a theodolite for repetition reading, having two clamping devices, both clamps are attached to the telescope, carrier, one serving to clamp the telescope to the base and the other to clamp the telescope to the horizontal graduated circle. Only one fine adjusting means is provided, this being secured to the telescope carrier for adjusting the telescope relatively to the base. The telescope carrier c is secured to the centre bearing b and has an extension c<1> constituting a casing for the horizontal circle d which extends from a sleeve d<1> frictionally mounted on the base a. A ring e rotatable on the base has an extension e<1> with an upward projection e<2> on one side of which bears the fineadjustment screw f<2> mounted on the casing c<1> while the other side of the projection e<2> bears on a spring plunger g'. Within the extension e<1> is a rod l and a screw m<1> so that by turning this screw the carrier c is clamped to the base. The clamp for the circle d comprises an eccentricallypivoted lever p operating a plunger o which is adapted to press a flexible disc n secured to the circle into contact with a member c<4> secured to the casing c<1>. In using the instrument for repetition reading, both clamps are loosened and the telescope directed towards the first object to be sighted. The clamp m<1> is then tightened and after fine adjustment by the screw f<2> a reading is taken. The clamp m<1> is then released, the telescope is directed towards the second object and another reading is taken. The clamp p is then tightened and the clamp m<1> released and the telescope is turned back to the first object, carrying the circle with it. The clamp m<1> is then tightened and the screw f<2> operated for fine adjustment and another reading taken. The clamp p is then released so that the whole proceeding can be repeated.