| The Columbia Encyclopedia, Sixth Edition. 2001-07. |
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| Hadley, John |
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| 16821744, English instrument maker. An optician by trade, Hadley built reflecting telescopes, based on Newtons model, that had greater resolution than the cumbersome refractors then in use. In 1731 he built a reflecting octant, based on Newtons sketch, that prefigured the modern nautical sextant. Hadley was a leading member of the Royal Society. |
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| | | The Columbia Encyclopedia, Sixth Edition. Copyright © 2007 Columbia University Press. |
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