{"method":"optical","year":1849,"researcher_1":"Fizeau","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Toothed wheel","mechanism_2":"","remark":"","speed":315300}
{"method":"optical","year":1872,"researcher_1":"Cornu","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Toothed wheel","mechanism_2":"","remark":"","speed":298500,"error":900}
{"method":"optical","year":1908,"researcher_1":"Perrotin","researcher_2":"Prim","researcher_3":"","researcher_4":"","mechanism":"Toothed wheel","mechanism_2":"","remark":"","speed":299901,"error":84}
{"method":"optical","year":1862,"researcher_1":"Foucault","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"","speed":298000,"error":500}
{"method":"optical","year":1874,"researcher_1":"Cornu","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"","speed":298500}
{"method":"optical","year":1878,"researcher_1":"Cornu","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"","speed":300400,"error":800}
{"method":"optical","year":1878,"researcher_1":"Michelson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"","remark":"","speed":300140,"error":700}
{"method":"optical","year":1879,"researcher_1":"Michelson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"","remark":"","speed":299910,"error":50}
{"method":"optical","year":1882,"researcher_1":"Newcomb","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"Using only those observations supposed to be nearly free from constant errors (Newcomb's choice)","speed":299860,"error":30}
{"method":"optical","year":1882,"researcher_1":"Newcomb","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"Using all observations (errors 30 or 50)","speed":299810,"error":45}
{"method":"optical","year":1882,"researcher_1":"Michelson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"Spherical fixed mirror","remark":"","speed":299853,"error":60}
{"method":"optical","year":1924,"researcher_1":"Michelson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"","remark":"","speed":299802,"error":30}
{"method":"optical","year":1926,"researcher_1":"Michelson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"","remark":"","speed":299796,"error":4}
{"method":"optical","year":1935,"researcher_1":"Michelson","researcher_2":"Pease","researcher_3":"Pearson","researcher_4":"","mechanism":"Rotating mirror","mechanism_2":"","remark":"","speed":299774,"error":11}
{"method":"electrical","year":1857,"researcher_1":"Weber","researcher_2":"Kohlrausch","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":310800}
{"method":"electrical","year":1868,"researcher_1":"Maxwell","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":284300}
{"method":"electrical","year":1869,"researcher_1":"Thomson","researcher_2":"King","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":280900}
{"method":"electrical","year":1874,"researcher_1":"McKichan","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":289700}
{"method":"electrical","year":1879,"researcher_1":"Ayrton","researcher_2":"Perry","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":296100}
{"method":"electrical","year":1880,"researcher_1":"Shida","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":295600}
{"method":"electrical","year":1883,"researcher_1":"JJThomson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":296400}
{"method":"electrical","year":1884,"researcher_1":"Klemencic","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":302000}
{"method":"electrical","year":1888,"researcher_1":"WThomson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":300500}
{"method":"electrical","year":1889,"researcher_1":"Rosa","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":300090}
{"method":"electrical","year":1890,"researcher_1":"JJThomson","researcher_2":"Searle","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":299690}
{"method":"electrical","year":1891,"researcher_1":"Pellat","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":301010}
{"method":"electrical","year":1892,"researcher_1":"Abraham","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":299220}
{"method":"electrical","year":1897,"researcher_1":"Hurmuzescu","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":300190}
{"method":"electrical","year":1898,"researcher_1":"Perot","researcher_2":"Fabry","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":299870}
{"method":"electrical","year":1899,"researcher_1":"Lodge","researcher_2":"Glazesbrook","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":301000}
{"method":"electrical","year":1907,"researcher_1":"Rosa","researcher_2":"Dorsey","researcher_3":"","researcher_4":"","mechanism":"Ratio of electromagnetic to electrostatic units","mechanism_2":"","remark":"","speed":299710,"error":30}
{"method":"electrical","year":1891,"researcher_1":"Blondlot","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Electromagnetic radiation in vacuo","mechanism_2":"Lecher wires","remark":" ","speed":297600}
{"method":"electrical","year":1895,"researcher_1":"Trowbridge","researcher_2":"Duane","researcher_3":"","researcher_4":"","mechanism":"Electromagnetic radiation in vacuo","mechanism_2":"Lecher wires","remark":"","speed":300300}
{"method":"electrical","year":1897,"researcher_1":"Saunders","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Electromagnetic radiation in vacuo","mechanism_2":"Lecher wires","remark":"","speed":299700}
{"method":"electrical","year":1899,"researcher_1":"MacLean","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Electromagnetic radiation in vacuo","mechanism_2":"Free space","remark":" ","speed":299100}
{"method":"electrical","year":1923,"researcher_1":"Mercier","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Electromagnetic radiation in vacuo","mechanism_2":"Lecher wires","remark":" ","speed":299700,"error":30}
{"method":"electro-optical","year":1928,"researcher_1":"Karolus","researcher_2":"Mittelstaedt","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"","remark":"","speed":299778,"error":20}
{"method":"electro-optical","year":1937,"researcher_1":"Anderson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"","remark":"","speed":299771,"error":12}
{"method":"electro-optical","year":1940,"researcher_1":"Huttel","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"","remark":"","speed":299768,"error":10}
{"method":"electro-optical","year":1941,"researcher_1":"Anderson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"","remark":"","speed":299776,"error":14}
{"method":"electro-optical","year":1950,"researcher_1":"McKinley","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Quartz modulator","mechanism_2":"","remark":"","speed":299780,"error":70}
{"method":"electro-optical","year":1950,"researcher_1":"Houstoun","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Quartz modulator","mechanism_2":"","remark":"","speed":299775,"error":9}
{"method":"radiowave","year":1947,"researcher_1":"Smith","researcher_2":"Franklin","researcher_3":"Whiting","researcher_4":"","mechanism":"Radar","mechanism_2":"","remark":"","speed":299695,"error":50}
{"method":"radiowave","year":1947,"researcher_1":"Jones","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radar","mechanism_2":"","remark":"","speed":299687,"error":25}
{"method":"radiowave","year":1949,"researcher_1":"Aslakson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radar","mechanism_2":"","remark":"","speed":299792.4,"error":2.4}
{"method":"radiowave","year":1949,"researcher_1":"Jones","researcher_2":"Cornford","researcher_3":"","researcher_4":"","mechanism":"Radar","mechanism_2":"","remark":"","speed":299701,"error":25}
{"method":"radiowave","year":1951,"researcher_1":"Aslakson","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radar","mechanism_2":"","remark":"","speed":299794.2,"error":1.4}
{"method":"radiowave","year":1947,"researcher_1":"Essen","researcher_2":"Gordon-Smith","researcher_3":"","researcher_4":"","mechanism":"Cavity resonator","mechanism_2":"","remark":"","speed":299792,"error":3}
{"method":"radiowave","year":1950,"researcher_1":"Essen","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Cavity resonator","mechanism_2":"","remark":"","speed":299792.5}
{"method":"radiowave","year":1950,"researcher_1":"Hansen","researcher_2":"Bol","researcher_3":"","researcher_4":"","mechanism":"Cavity resonator","mechanism_2":"","remark":"","speed":299789.3,"error":0.8}
{"method":"geodetic","year":1949,"researcher_1":"Bergstrand","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299796,"error":2}
{"method":"geodetic","year":1950,"researcher_1":"Bergstrand","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299793.1,"error":0.26}
{"method":"geodetic","year":1951,"researcher_1":"Bergstrand","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299793.1,"error":0.4}
{"method":"geodetic","year":1954,"researcher_1":"Mackenzie","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299792.3,"error":0.5}
{"method":"geodetic","year":1955,"researcher_1":"Scholdstrom","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299792.4,"error":0.4}
{"method":"geodetic","year":1956,"researcher_1":"Edge","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299792.4,"error":0.11}
{"method":"geodetic","year":1956,"researcher_1":"Edge","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299792.2,"error":0.13}
{"method":"geodetic","year":1956,"researcher_1":"Waller","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Geodimeter","remark":"Improved by Bergstrand","speed":299792.5}
{"method":"spectroscopy","year":1952,"researcher_1":"Rank","researcher_2":"Ruth","researcher_3":"VandenSluis","researcher_4":"","mechanism":"Bombarding molecule with electomagnetic radiation","mechanism_2":"HCN molecule","remark":"","speed":299776,"error":6}
{"method":"spectroscopy","year":1954,"researcher_1":"Rank","researcher_2":"Shearer","researcher_3":"Wiggins","researcher_4":"","mechanism":"Bombarding molecule with electomagnetic radiation","mechanism_2":"HCN molecule","remark":"","speed":299789.8,"error":3}
{"method":"spectroscopy","year":1955,"researcher_1":"Plyler","researcher_2":"Blaine","researcher_3":"Cannon","researcher_4":"","mechanism":"Bombarding molecule with electomagnetic radiation","mechanism_2":"CO molecule","remark":"","speed":299792,"error":6}
{"method":"spectroscopy","year":1956,"researcher_1":"Rank","researcher_2":"Bennett","researcher_3":"Bennett","researcher_4":"","mechanism":"Bombarding molecule with electomagnetic radiation","mechanism_2":"HCN molecule","remark":"","speed":299791.9,"error":2}
{"method":"geodetic","year":1956,"researcher_1":"Wadley","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Tellurometer","remark":"Uses microwave radiation","speed":299792.9}
{"method":"geodetic","year":1956,"researcher_1":"Wadley","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Tellurometer","remark":"Uses microwave radiation","speed":299792.7,"error":2}
{"method":"geodetic","year":1957,"researcher_1":"Wadley","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Kerr cell","mechanism_2":"Tellurometer","remark":"Uses microwave radiation","speed":299792.6,"error":1.2}
{"method":"ultrasonic modulation","year":1966,"researcher_1":"Karolus","researcher_2":"Helmberger","researcher_3":"","researcher_4":"","mechanism":"Quartz modulator","mechanism_2":"Immersed in liquid","remark":"","speed":299792.1,"error":0.2}
{"method":"ultrasonic modulation","year":1967,"researcher_1":"Karolus","researcher_2":"Helmberger","researcher_3":"","researcher_4":"","mechanism":"Quartz modulator","mechanism_2":"Immersed in liquid","remark":"Correction for error in 1966 measurement of the base length","speed":299792.44,"error":0.2}
{"method":"interferometry","year":1951,"researcher_1":"Froome","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radio wave","mechanism_2":" ","remark":"","speed":299792.6,"error":0.7}
{"method":"interferometry","year":1954,"researcher_1":"Froome","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radio wave","mechanism_2":" ","remark":"","speed":299793,"error":0.3}
{"method":"interferometry","year":1958,"researcher_1":"Froome","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radio wave","mechanism_2":"","remark":"Correction of 1954","speed":299792.75,"error":0.3}
{"method":"interferometry","year":1954,"researcher_1":"Florman","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radio wave","mechanism_2":" ","remark":"","speed":299795.1,"error":3.1}
{"method":"interferometry","year":1958,"researcher_1":"Froome","researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Radio wave","mechanism_2":" ","remark":"","speed":299792.5,"error":0.1}
{"method":"interferometry","year":1967,"researcher_1":"Simkin","researcher_2":"Lukin","researcher_3":"Sikora","researcher_4":"Strelenskii","mechanism":"Microwave","mechanism_2":"","remark":"","speed":299792.56,"error":0.11}
{"method":"spectroscopy","year":1972,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 0.633 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4622,"error":0.018}
{"method":"spectroscopy","year":1972,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 3.39 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4574,"error":0.0013}
{"method":"spectroscopy","year":1972,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 3.39 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.458,"error":0.002}
{"method":"spectroscopy","year":1976,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 3.39 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4584,"error":0.0001}
{"method":"spectroscopy","year":1977,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 9.3 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4578,"error":0.0023}
{"method":"spectroscopy","year":1978,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 9.3 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4589,"error":0.0006}
{"method":"spectroscopy","year":1978,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 3.39 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4583,"error":0.0017}
{"method":"spectroscopy","year":1983,"researcher_2":"","researcher_3":"","researcher_4":"","mechanism":"Stabilized lasers","mechanism_2":"Wavelength 0.633 micrometres","remark":"Sub-Doppler saturated absorption spectroscopy","speed":299792.4587,"error":0.0004}