Setting Standards

Transit observers were stationed all over the world, yet were meant to take measurements that could be compared and combined. Could the work of so many scattered individuals be trusted? Could they produce reliable observations without direct supervision?
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The Astronomer Royal, Nevil Maskelyne, sought to provide a framework of common standards. He issued a guide for observers, detailing the procedures to be followed. This copy of his Instructions relative to the Observation of the ensuing Transit of the Planet Venus over the Sun’s Disk (1768) has elementary notes by an early reader.
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