User:Egil/Sandbox/Earth
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Work in progress.
| Who | Year | Size reported | Error | Comment |
| Pythagoras | ~500 BC | None | Believed the Earth was a sphere | |
| Plato | ~400 BC | 400,000 stadia | +85% | First estimate of the size of Earth.
Note that for all stadia measures, there is uncertainty with regards to to the actual stadia used. The value used here is 185 m. |
| Archimedes | ~250 BC | 300,000 stadia | +55% | |
| Eratosthenes, Egypt | ~200 BC | 250,000 stadia | +15% | A value of 252,000 is also seen |
| Vitruvius | ~100 BC | 31,500,000 passus | +15% | Converting Eratoshenes results of 252,000 stadia into Roman measures |
| Posidonius, Egypt and Rhodes | ~100 BC | 240,000 stadia | +4% | He made major errors both in the distance and in difference in latitude between the two measuring points. These happend to cancel each other, achieving an amazingly accurate result. |
| Ptolemy | ~150 | 180,000 stadia | -17% | He corrected the distance, but kept the latitude measurement of Posidonius, and ended up with a significantly more inaccurate result. His result would be very influential, and was probably the reason Christopher Columbus underestimated the size of the Earth. |
| Abelseda, Arabia | 827 | [Stone] reports a radius of 3804.6 miles | ||
| Albazen, Arabia | 1100 | [Stone] reports a radius of 3774.4 miles | ||
| Jean Fernel, France | 1528 | 56746 toise per degree | -0.5% | Measured between Paris and Amiens, counting the revolutions of a carriage wheels to measure the distance. [Butterfield] reports a radius of 4006.9 miles. |
| Gerardus Mercator | ~1550 | (to be determined) | ||
| Willebrord Snell (Snellius), Holland | 1617 | 55100 toise per degree | -4% | Measured between Alkmaar and Bergen op Zoom. EB says 117,449 yards per degree (107.395 km). Hoefer 1873, says 4000 meter in error per degree, which is in conformance. |
| Richard Norwood, England | 1635 | 3984.6 mile radius | [Stone] and [Butterfield] reports the radius. French sources say 57300 toise per degree. | |
| Giovanni Battista Riccioli, Lombardy | 1661 | 321815 Bologna feet per degree | +10% | Assuming a Bologna foot is 38 cm, the result is 122.29 km per degree. [Hoefer] says more than 10000 meter in error, which confirms this. [Butterfield] reports a radius of 4265.9 miles. |
| Jean Picard, France | 1670 | 57060 toise per degree | +0.1% | [Stone] reports a radius of 3957.6 miles |
| Jacques Cassini, France | 1718 | 57097 toise per degree | +0.2% | [Stone] reports a radius of 3984.2 miles |
| Lapland expedition | 1736 | 57438 toise per degree | ||
| Pierre Louis Maupertuis and Pierre Bouguer, French Academy of Sciences | 1737 | (coordinate w/expeditions, details tbd) | ||
| Lacaille and Cassini de Thury, France | 1740 | 57027 toise per degree | +0.03% | |
| Peru expedition | 1745 | 56748 toise per degree | ||
| Delambre and Méchain, France | 1799 | 20522960 toise | Original definition of the metre, measured between Dunkerque and Barcelona. | |
| Current value | 40009152 m | 0% |
[edit] References
- Ferdinand Hoefer: Historie de l'astronomie, Paris 1873
- Edmund Stone: The Construction and Principal Uses of Mathematical Instruments, J. Richardson in Pater-Noster Row, London 1758.
- Arthur D. Butterfield: A History of the Determination of the Figure of the Earth from Arc Measurements, the Davis Press in Worcester, Massachusetts 1906.
