Dodwell's Data Table
DATE OBSERVATION OBLIQUITY REMARKS B.C. 2045 Karnak 25° 09' 55" summer solstice, sunset orientation B.C. 1570 Karnak 24° 32' 06" summer solstice, sunset orientation B.C. 1100 ancient Chinese 24° 13' 56" ancien observation, derived from "Chou-Pei" B.C. 1100 ancient Chinese 23° 54' 04" ascribed to Chou Kung, but corresponds to later date B.C. 900 ancient Hindu 24° 11' 04" derived from Jaina Astronomical Treatise "Suryaprajnapti" B.C. 700 ancient Chinese 24° 02' 06" derived from "Chou-Pei" B.C. 700 ancient Chinese 24° 01' 50" derived from "Chou-Pei" MEAN 24° 01' 58" B.C. 558 Thales 24° 00' 56" observations at Miletus B.C. 510 ancient Hindu 24° 00' 44" derived from the "Suryasiddhanta" B.C. 326 Pytheas 23° 53' 46" observations at Marseilles B.C. 326 Pytheas 23° 54' 53" observations at Marseilles MEAN 23° 54' 20" B.C. 230 Eratosthenes 23° 52' 04" observations at Alexandria B.C. 230 Eratosthenes 23° 51' 47" observations at Syene at Summer Soltice B.C. 230 Eratosthenes 23° 51' 59" observations at Syene at both Soltices B.C. 230 Eratosthenes 23° 52' 12" observations of shadowless area at Summer Solstice MEAN 23° 52' 00" B.C. 135 Hipparchus 23° 52' 16" observations at Rhodes B.C. 130 ancient Chinese 23° 54' 04" from figures given by Haui-Nan-Tzu (died B.C. 122) B.C. 80 ancient Chinese 23° 53' 46" observations at Loyang. Figures given by Lieou Hiang A.D. 80 Chinese 23° 54' 04" from figures given by the authors of the See-fen Astronomy, but result corresponds to earlier date of observation A.D. 139 Ptolemy 23° 48' 16" observations at Alexandria A.D. 521 Chinese 23° 40' 36" observations at Nanking (9 foot gnomon) A.D. 521 Chinese 23° 41' 59" observations at Nanking (8 foot gnomon) A.D. 521 Chinese 23° 41' 31" observations by Ouey Tartars at Kaifeng-fu, probably MEAN 23° 41' 22" A.D. 578 Chinese 23° 41' 12" observations at Sianfu A.D. 579 Chinese 23° 41' 12" observations at Sianfu A.D. 581 Chinese 23° 41' 12" observations at Sianfu A.D. 584 Chinese 23° 41' 30" observations at Loyang A.D. 596 Chinese 23° 42' 12" observations at Sianfu A.D. 597 Chinese 23° 42' 12" observations at Sianfu A.D. 629 Chinese 23° 40' 07" observations by Litchou-foung at Sianfu A.D. 829 Al Mamun 23° 35' 00" observations at Bagdad A.D. 880 Al Battani 23° 35' 54" observations at Rakka in Syria A.D. 916 Arab 23° 35' 50" mean of numerous Arab observations from A.D.829-1019 A.D. 1000 Ibn Junis 23° 36' 11" observations at Cairo A.D. 1049 - 1052 Chinese 23° 33' 40" observations as Kaifeng-fu A.D. 1070 Alzarkali 23° 34' 42" observations at Toledo A.D. 1100 Chinese 23° 34' 32" observations at Kaifeng-fu A.D. 1130 Chinese 23° 31' 48" observations at Hang Chow A.D. 1140 Almaeon 23° 34' 12" observations at Toledo A.D. 1174 Ben Maimon 23° 31' 51" observations at Cordova A.D. 1250 Alphonsine Tables 23° 33' 11" observations at Toledo A.D. 1277-1280 Chinese 23° 33' 02" observations by Ko-Chou-King at Peking A.D. 1290 Nasar-Al-Din 23° 31' 40" observations at Maragha (Persia) A.D. 1290 Guilliame de St. Cloud 23° 34' 00" observation at Paris A.D. 1328 Prophatius Judaeus 23° 32' 42" observations at Toledo A.D. 1332 Jean de Lignieres 23° 33' 31" observations at Paris A.D. 1363 Ibn al Shatir 23° 32' 32" observations at Cairo A.D. 1437 Ulugh Beigh 23° 31' 44" observations at Samarkand A.D. 1460 Purbach and Regiomontanus 23° 30' 37" observations at Erfurt, Nurnberg, and Vienna A.D. 1468 Toscanelli 23° 31' 47" observations at Florence A.D. 1491 Walther 23° 30' 50" observations at Nurnberg A.D. 1491 Novarra 23° 30' 56" observations at Bologna A.D. 1514 Werner 23° 30' 33" observations at Nurnberg A.D. 1525 Copernicus 23° 30' 30" observations at Frauenberg A.D. 1570 Ignatius 23° 29' 00" observations at Bologna (corrections uncertain) A.D. 1570 Dante Prince of Hess 23° 31' 00" observations at Cassel (corrections uncertain) A.D. 1570 Rothmann & Byrge 23° 30' 20" observations at Cassel (corrections uncertain) MEAN 23° 30' 07" A.D. 1587 Tycho Brahe 23° 29' 49" observations at Uraniborg A.D. 1594 Wright 23° 30' 00" observations at Cambridge A.D. 1616 Wendelin 23° 30' 16" observations at Forcalquier in the Basses Alpes A.D. 1627 Kepler 23° 30' 30" observations at Linz (Upper Austria) A.D. 1636 Peiresc 23° 30' 23" observations at Marseilles A.D. 1636 Gassendi 23° 29' 58" observations at Marseilles A.D. 1650 Riccioli 23° 29' 40" observations at Bologna A.D. 1658 Hevelius 23° 29' 27" observations at Danzig A.D. 1664 Cassini 23° 29' 08" observations at Bologna and Paris A.D. 1686 Wurzelbaur 23° 28' 52" observations at Nurnberg A.D. 1660 Montons 23° 29' 03" Hutton A.D. 1672 Richer 23° 28' 52" Hutton A.D. 1686 La Hire 23° 29' 28" Hutton A.D. 1689.5 Flamsteed 23° 28' 56" Ball's Astronomy A.D. 1690 Flamsteed 23° 28' 48" Encyclopaedia Britannica A.D. 1690 Flamsteed 23° 29' 00" Hutton MEAN 23° 28' 55" A.D. 1703 Bianchini 23° 28' 35" Encyclopaedia Britannica A.D. 1703 Bianchini 23° 28' 25" Hutton MEAN 23° 28' 30" A.D. 1706 Roemer 23° 28' 41" Hutton A.D. 1715 Louville 23° 28' 24" Hutton A.D. 1730 Godin 23° 28' 20" Hutton A.D. 1736 Condamine 23° 28' 24" Encyclopaedia Britannica A.D. 1743 Cassini de Thury 23° 28' 26" Encyclopaedia Britannica A.D. 1750 Lacaille 23° 28' 19" Encyclopaedia Britannica A.D. 1750 Bradley 23° 28' 18" Hutton A.D. 1755 Bradley 23° 28' 15" Encyclopaedia Britannica A.D. 1756 Mayer 23° 28' 16" Encyclopaedia Britannica and Hutton A.D. 1769 Maskelyne 23° 28' 10" Encyclopaedia Britannica and Hutton A.D. 1772 Hornsby 23° 28' 08" Hutton A.D. 1779 Nautical Almanac 23° 28' 07" Hutton A.D. 1780 Cassini 23° 27' 54" Encyclopaedia Britannica A.D. 1795 Maskelyne 23° 27' 58" Ball's Astronomy A.D. 1800 Nautical Almanac 23° 27' 50" Hutton A.D. 1800 Maskelyne 23° 27' 57" Encyclopaedia Britannica and Hutton A.D. 1800 Piazzi 23° 27' 56" Encyclopaedia Britannica and Hutton A.D. 1800 Pond 23° 27' 56" Hutton A.D. 1800 Delambre 23° 27' 57" Encyclopaedia Britannica and Hutton -- hundreds of observations A.D. 1800 Bessel 23° 27' 55" Ball's Astronomy A.D. 1812 English and French Astronomers 23° 27' 42" Hutton A.D. 1813 Pond 23° 27' 49" Encyclopaedia Britannica A.D. 1813 Brinkley 23° 27' 50" Ball's Astronomy A.D. 1813 Arago and Mathieu 23° 27' 49" Grant (History of Physical Astronomy) A.D. 1815 Bessel 23° 27' 48" Encyclopaedia Britannica A.D. 1816 Brinkley 23° 27' 49" Encyclopaedia Britannica A.D. 1825 Pearson 23° 27' 44" Encyclopaedia Britannica A.D. 1835 Airy 23° 27' 40" Encyclopaedia Britannica A.D. 1850 Leverrier 23° 27' 32" Encyclopaedia Britannica A.D. 1868 Airy 23° 27' 22" Ball's Astronomy A.D. 1880 Nautical Almanac 23° 27' 17.6" A.D. 1900 Nautical Almanac 23° 27' 08" A.D. 1920 Nautical Almanac 23° 26' 58.9" A.D. 1940 Nautical Almanac 23° 26' 49.5" A.D. 1949 Nautical Almanac 23° 26' 45.3"