AAS 203rd Meeting, January 2004
Session 35 HAD III
Division Oral, Monday, January 5, 2004, 2:00-3:30pm, Regency V

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[35.06] Remeasuring the Alignment of the Nantucket Meridian Line

P.B. Boyce (Maria Mitchell Obs.), A. Davis (SUNY at Plattsburgh and Maria Mitchell Obs.)

In 1840, William Mitchell (the father of Maria Mitchell) surveyed the N-S meridian of the town of Nantucket, and erected two meridian stones to delineate true north. We have previously shown (L. Amory, et. al., BAAS, 34, 1159, 2002) that the stones were erected as a means of facilitating the calibration of surveyor’s compasses for magnetic declination. The Nantucket meridian stones were apparently erected in response to a resolution of the legislature of the Commonwealth of Massachusetts in 1830 requiring all towns ``to make ...accurate Plans of their respective towns...". The first known detailed map of Nantucket was completed by William Mitchell in 1838. During the summer of 2003 we remeasured the Nantucket meridian stones using a relatively modern K&E transit instrument to make Polaris sights. Our determinations have an accuracy of 0.6 minutes of arc, which should be comparable to the accuracy with which the stones would have been set originally. The stones are now 3.5 +- 0.8 minutes of arc off of the N-S line, or about 4 inches of displacement.

We believe that William Mitchell could achieve better accuracy than this. His positional observations of stars won praise from the US Naval Observatory. The discrepancy from the N-S line might be explained by movement of the stones since 1840. We know that the south stone was recently removed for construction and replaced. In this case, its position was triangulated before removal with a modern laser theodolite, and it was supposed to be reset to within a few millimeters. However, it is possible that earlier, undocumented construction, such as the installation of sidewalks and curbs, resulted in a four inch shift in position of one or both stones. This project was supported by the NSF/REU grant AST-0097694 and the Nantucket Maria Mitchell Association.

If you would like more information about this abstract, please follow the link to http://www.aas.org/~pboyce/mma/stones.htm. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: pboyce@aas.org

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Bulletin of the American Astronomical Society, 35 #5
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