2010. National Geophysical Data Center. This shapefile shows lines of equal annual change (secular variation) in the inclination of the Earth's magnetic field, derived from the Internatio... National Atlas of the United States.
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2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation), in the total field intensity of the Earth's magnetic field, derived fro... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation) in the vertical component of the total field intensity of the Earth's ma... National Atlas of the United States.
2010. National Geophysical Data Center. This shapefile contains isodynamic lines (lines of equal total intensity of the Earth's magnetic field), derived from the International Geomagnetic... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal vertical intensity of the Earth's magnetic field, derived from the International Geomagnetic Reference Fie... National Atlas of the United States.
1999. Geological Survey (U.S.). This line shapefile portrays the major roads in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the i... Geological Survey (U.S.).
47. Map of Boston
1890. 1 map ; 39 x 32 cm.
1839. Burr, David H., 1803-1875. Detailed map showing relief by hachures, drainage, township and county boundaries, cities and towns, canals, road, and railroads. From his The Amer... (London], ).
1847. Mitchell, S. Augustus (Samuel Augustus), 1792-1868. Longitude in degrees west from Greenwich and east from Washington, D.C.; latitude in degrees north from equator.; Colored by county; borders of sta... S.A . Mitchell (Philadelphia, Pa).
1890. Appalachian Mountain Club. 1 map : col. ; 59 x 84 cm Relief shown by countours and spot heights. "Contour interval 20 feet.".