Speed of light Experiments

These charts have been copied from the site of Barry Setterfield...

Further comprehensive details about these experiments can be found there as well.

[ figures in red are given to experiments where a value of exactly 300,000 m/s would be within the accepted posted range ]

TABLE 1 Roemer-type Experiments

Authority Date Seconds delay Value of c Km/sec Comment *Roemer 1673 ± 5     ?                     317,700 Corrected method *Newton 1706   480 311,660 Approximate value    Delambre 1738 ± 71   493.2 303,320 ± 310 Mean of 1000 observs.    Martin 1759   493.0 303,440      Price 1770   492.0 304,060      Encyc. Brit. 1771   495.0 302,220 Accepted value   #Bode 1778   487.5 306,870     #Boscovich 1785   486.0 307,810      Glasenapp 1861 ± 13   498.57 300,050 ± 60 Mean of 320 observs.    Sampson 1877 ± 32   498.64 300,011 Private reduction    Harvard 1877 ± 32   498.79 299.921 ± 13 Harvard reduction adding this comparative entry into Barry Setterfeild's...    Waterman 2002   498.6583 300,000 theorectical

Table 4 – Bradley Method Values  (Aberration) Pulkova observations  (used in Fig. 1) indicated by *

Average year Date of observation Observer Value of K in arc seconds Value of c in Km/sec 1740 1726-1754 Bradley: Reworked avg. 20.437 300,650 1783 1750-1816 Lindenau: ±from weights 20.450 ± 0.011 300,460 ± 170 1841* 1840-1842 Struve: corrected 1853 20.463 ± 0.017 300,270 ± 250 1841* 1840-1842 Folks-Struve 20.458 ± 0.008 300,340 ± 120 1843* 1842-1844 Struve 20.480 300,020 1843 1842-1844 Lindhagen-Schweizer 20.498 ± 0.012 299,760 ± 180 1858 1842-1873 Nyren-Peters 20.495 ± 0.013 299,800 ± 190 1864.5 1862-1867 Newcomb: weighted avg. 20.490 299,870 1866.5 1863-1870 Gylden 20.410 301,050 1868 1863-1873 Nyren and Gulden 20.52 299,440 1870 1861-1879 Nyren – Wagner 20.483 ± 0.003 299,980 ± 50 1873 1871-1875 Nyren 20.51 299,580 1879.5 1879-1880 Nyren 20.52 299,440 1880.5 1879-1882 Nyren 20.517 ± 0.009 299,480 ± 130 1883* 1883-1883 Nyren: weighted average, all observations 20.491 ± 0.006 299,850 ± 90 1889.5 1889-1890 Kustner 20.490 ± 0.018 299,870 ± 260 1889.5 1889-1890 Marcuse 20.490 ± 0.012 299,870 ± 180 1889.5 1889-1890 Doolittle 20.450 ± 0.009 300,460 ± 130 1890.5 1890-1891 Comstock 20.443 ± 0.011 300,560 ± 170 1891.5 1890-1893 Becker 20.470 300,170 1891.5 1891-1892 Preston 20.430 300,750 1891.5 1891-1892 Batterman 20.507 ± 0.011 299,630 ± 170 1891.5 1891-1892 Marcuse 20.506 ± 0.009 299,640 ± 130 1891.5 1891-1892 Chandler 20.507 ± 0.011 299,630 ± 170 1892.5 1891-1894 Becker 20.475 ± 0.012 300,090 ± 180 1893 1892-1894 Davidson 20.480 300,020 1894.5 1894-1895 Rhys-Davis 20.452 ± 0.013 300,430 ± 190 1896 1893-1899 Rhys-Jacobi-Davis 20.470 ± 0.010 300,170 ± 150 1896.5 1896-1897 Rhys-Davis 20.470 ± 0.011 300,170 ± 170 1897 1897-1897 Grachev-Kowalski 20.471 ± 0.007 300,150 ± 100 1898.5 1898-1899 Rhys-Davis 20.470 ± 0.011 300,170 ± 170 1898.5 1898-1899 Grachev 20.524 ± 0.007 299,380 ± 100 1899 1899-1899 Grachev 20.474 ± 0.007 300,110 ± 100 1900.5 1900-1901 Int’n’l Latitude Service 20.517 ± 0.004 299,480 ± 60 1901.5 1901-1902 Doolittle 20.513 ± 0.009 299,540 ± 130 1901.5 1901-1902 Int’n’l Latitude Service 20.520 ± 0.004 299,440 ± 60 1903 1903-1903 Doolittle 20.525 ± 0.009 299,360 ± 130 1904.5 1904-1905 Ogburn 20.464 ± 0.011 300,250 ± 170 1905 1905-1905 Doolittle: weighted avg. 20.476 ± 0.009 300,080 ± 130 1905 1904-1906 Bonsdorf 20.501 ± 0.007 299,710 ± 100 1906 1906-1906 Doolittle: weighted avg. 20.498 ± 0.009 299,760 ± 130 1906.5 1904-1909 Bonsdorf et.al. 20.505 ± 0.008 299,650 ± 120 1907 1907-1907 Doolittle 20.504 ± 0.009 299,670 ± 130 1907 1906-1908 Bayswater 20.512 ± 0.007 299,550 ± 100 1907.5* 1907-1908 Orlov 20.491 ± 0.008 299,860 ±120 1907.5 1907-1908 Int’n’l Latitude Service 20.525 ± 0.004 299,360 ± 60 1908 1908-1908 Doolittle 20.507 ± 0.012 299,630 ± 180 1908.5* 1908-1909 Semanov 20.518 ± 0.010 299,460 ± 150 1908.5 1908-1909 Int’n’l Latitude Service 20.522 ± 0.004 299,410 ± 60 1909 1909-1909 Doolittle 20.520 ± 0.009 299,440 ± 130 1909.5* 1904-1915 Zemtsov 20.500 299,730 1909.5* 1909-1910 Semenov 20.508 ± 0.013 299,610 ± 190 1910 1910-1910 Doolittle 20.501 ± 0.008 299,710 ± 120 1914* 1913-1915 Numerov 20.506 299,640 1916* 1915-1917 Tsimmerman 20.514 299,520 1922* 1915-1929 Kulikov 20.512 ± 0.003 299,550 ± 50 1923.5 1911-1936 Spencer-Jones 20.498 ± 0.003 299,760 ± 50 1926.5 1925-1928 Berg 20.504 299,670 1928 1928-1928 Spencer-Jones 20.475 ± 0.010 300,090 ± 150 1930.5 1930-1931 Spencer-Jones 20.507 ± 0.004 299,630 ± 60 1933 1915-1951 Sollenberger 20.453 ± 0.003 300,420 ± 50 1935* 1929-1941 Romanskaya 20.511± 0.007 299,570 ± 100 1935.5 1926-1945 Rabe (gravitational) 20.487 ± 0.003 299,920 ± 50 adding this comparative entry into Barry Setterfeild's... 2002.9 1947- Waterman (theorectical) 20.482 ± 0.001 300,000 ± 0 Table 5 Toothed Wheel Experimental Values (NOED = number of experiments done) starred values are generally considered the most reliable

Experimenter Date NOED Base line in meters c value in Km/sec Comments  Fizeau 1849.5   28    8633 315,300 Base too short (journals)  Fizeau 1849.5   28    8633 313,300 Base too short (textbooks)  Fizeau 1855      8633 305,650 No reference – usually omitted  Fizeau 1855      8633 298,000 Bad date citation for Foucault?  Cornu 1872  658 10,310 298,500 ± 300 Rejected by Cornu – serious errors  Cornu 1874.8  624 22,910 300,400 ± 300 Flawed analysis – 4 figures only *Cornu/Helmert 1874.8  624 22,910 299,990 ± 200 Reworked in 1876 – generally accepted *Cornu/Dorsey 1874.8  624 22,910 299,900 ± 200 Reworked by Dorsey in 1944  Young/Forbes 1880   12    5551.07 301,382 Usually severely criticized  Perrotin/Prim 1900.4 1540 11,862.2 300,032 ± 215 1908 – discarded by Prim *Perrotin 1900.4 1540 11,862.2 299,900 ± 80 Perrotin’s published 1900 analysis  Perrotin 1901.4     299,880 ± 50 Perrotin’s generally accepted mean *Perrotin 1902.4 2465 45,950.7 299,860 ± 80 Perrotin’s published 1902 analysis *Perrotin 1902.4 2465 45,950.7 299,901 ± 84 Prim’s final declared value Table 6 Rotating Mirror Experiments (NOED = number of experiments done)

Experimenter	Date	NOED	Faces	Base (meters)	Rev/sec	Deflection	c value in Km/s
1.  Focault	1882.8	80	1	20.0	500	0.7 mm	298,000    ± 500
2.  Michelson	1878.0	10	1	152.4	130	7.58 mm	300,140    ± 480
3.  Michelson	1879.5*	100	1	605.4	257.3	133.20 mm	299,910    ± 50
4.  Newcomb-mean	1881.8	255	4	2550.95	114-268	18 cm av.	299,810
5.  Newcomb	1882.7*	66	4	3721.21	176-268	18 cm av.	299,860    ± 30
6.  Michelson	1882.8*	563	1	624.645	129-259	138 mm av.	299,853    ± 60
7.  Michelson	1924.6*	80	8	35,426.23	528	Nil	299,802    ± 30
8.  Michelson	1926.5*	1600	8-16	35,426.23	264-528	Nil	299,798    ± 15
9.  Pease/Pearson	1932.5*	2885	32	1,610.4	585-730	0.01 mm av.	299,774    ± 10

Comments 1. Foucault:  Micrometer and diffraction problems coupled with miniscule deflection. 2. Michelson:  Value discarded by Michelson – large probable error and crude equipment. 3. Michelson:  Number of experiments listed as 100, but there were ten sets per experiment. 4. Newcomb:  This mean resulted from the inclusion of two series whose results Newcomb rejected as unreliable due to systematic errors (mirror imbalance and vibration).  These results were 299,627 Km/s in 1880.9 and 299,694 Km/s in 1881.7, both for air.  They were included with the final reliable value to get a vacuum mean only in order to avoid criticism.  These figures give the average displacement and range of rotation rates and the total number of experiments conducted.  The smaller path is quoted. 5. Newcomb:  Definitive value.  He insisted that his results “should depend entirely on the measures of 1882.” 6. Michelson:  This 1882.8 result was obtained with the same equipment as his 1879.5 result.  This value is lower. 7. Michelson:  Essentially a new method.  An octagonal glass prism with a rotation rate giving no deflection. 8. Michelson:  Polygonal mirrors of 8, 12, and 16 faces.  Result corrected for group velocity.  Equipment the same as for 1924.6.  This new method registered a decay in c over two years approximately equal to 2 Km/s per year. 9. Pease/Pearson:  Unstable baseline and minute deflection giving micrometer problems.  Generally disregarded today.