Scribing, Graduation, and Calibration of U.S. Coast and Geodetic Survey Leveling Rods from 1877 to 1968

摘要

Precise leveling by the U.S. Coast and Geodetic Survey (C&GS) began in 1877. Until the early 1970's most leveling surveys by C&GS and its successor organizations employed level rods that were designed, constructed, scribed, and graduated by C&GS. From 1877 through 1923, C&GS also calibrated the rods. From 1924 until 1968, calibrations were carried out by the National Bureau of Standards (NBS). This report describes the methods and results of scribing, graduating, and calibrating these rods from 1877 until 1968 when the last calibrations were made. Four types of rods are discussed: brass target rods used from 1877 through 1894, paraffin-saturated wooden target rods used from 1895 through 1898, paraffin-saturated wooden Fischer rods used from 1899 through 1915, and Fischer Invar-scale rods used from 1916 until the early 1970's.