ಗ್ರೇಟ್ ಟ್ರಿಗ್ನಾಮೆಟ್ರಿಕ್ ಸರ್ವೆ: ಪರಿಷ್ಕರಣೆಗಳ ನಡುವಿನ ವ್ಯತ್ಯಾಸ
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Vikashegde (ಚರ್ಚೆ | ಕಾಣಿಕೆಗಳು) No edit summary |
Vikashegde (ಚರ್ಚೆ | ಕಾಣಿಕೆಗಳು) |
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೧೫ ನೇ ಸಾಲು:
==ಉಪಕರಣಗಳು ಮತ್ತು ಬಳಸಿದ ವಿಧಾನಗಳು==
[[File:Ramsden_zenith_sector.jpg|thumb|left|upright|A [[Zenith sector]] was an upward facing telescope with accurate angle measurement scales. A star close to the zenith of known declination from the pole star was used to determine latitude as a direct measurement of the pole star could be affected by refraction.]]
Triangulation surveys were based on a few carefully measured baselines and a series of angles. The initial baseline was measured with great care since the accuracy of the subsequent survey was critically dependent upon it. Various corrections were applied, principally temperature. An especially accurate folding chain was used, laid on horizontal tables, all shaded from the sun and with constant tension. The early surveys made use of large and bulky theodolites made by William Carey, a Zenith sector made by Jesse Ramsden and 100-foot (30 m) chains. Later surveys used more compact theodolites.
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