MEASUREMENT OF LINES IN POLYGONOMETRIC OPERATIONS WITH LENGTH FINDER AD-1 (IZMERENIE LINII V POLIGONOMETRICHESKIKH KHODAKH DLINOMEROM AD-1),
AERONAUTICAL CHART AND INFORMATION CENTER ST LOUIS MO LINGUISTIC SECTION
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The translation is a description of the length-finder AD-1 and the method used in finding the measurement of lines in first and second order polygonometry. Without this instrument it is necessary to use graduated tapes and steel or Invar wires and a great amount of field work in laying out, fastening, and leveling of intermediate points. The AD-1 length finder consists of a calibrated measuring disc enclosed in a duraluminum frame, with a counting register and a braking device. Fastened to the frame of the instrument, on one surface are two directing rollers with thin grooves, by means of which the wire in its tense condition leads to the measuring disc and wraps around it. The axis of the rollers and the measuring disc rotate freely on ball-bearings. There are two slots in the frame for inserting the wire into the instrument. Two indexes may be brought into coincidence with points. The length-finder weighs about 2.2 kg. The essence of the method used consists of the determination of the length of an unstandardized steel wire, which is stretched beforehand between fixed points. The determination is accomplished by moving the length-finder along the wire, as a result of which the length of the line is automatically measured. It has been established that the method can be recommended for measurement of lines in first and second order traverse, and also in theodolite traverse. It completely eliminates the necessity of laying out, fastening and leveling intermediate points on the lines.