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Media Types: Collections- Media Types: Collections
- Media Types: Collections
- Groups: Head, Clara and Maria Township Maps
- Year: 1859
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- Head Township ca.1859
Early surveyors, like William E. Logan, used Rochon micrometer telescopes and targets (disk on a calibrated pole) to measure distance. Each microscope had a different calibration and therefore a different range. The instruments were calibrated against a distance measured with a surveyors chain (also known as Gunter’s chain). One chain … Early surveyors, like William E. Logan, used Rochon micrometer telescopes and targets (disk on a calibrated pole) to measure distance. Each microscope had a different calibration and therefore a different …Head, Clara and Maria Public Library
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