The apparent path of Venus as it transits the face of the Sun depends on the position of the observer on Earth. This diagram from James Ferguson’s Astronomy explained upon Sir Isaac Newton’s Principles shows how slight are these differences, and suggests how difficult they were to measure.
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The straight lines on the large solar semicircle are the predicted tracks of Venus in 1761, as seen from London, the eastern mouth of the Ganges in India, St Helena in the Atlantic, and Bencoolen (now Bengkulu in Sumatra, Indonesia). |
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