NGA Facilities Operating Status »
Contact Us »


Nathaniel Bowditch


In 1802, Nathaniel Bowditch, a mathematician and astronomer from Salem, Massachusetts, published “The New American Practical Navigator,” which corrected more than 8,000 errors in the tables of the most popular navigational text of the time. Bowditch billed his work as the “epitome of navigation.” In 1866, the Hydrographic Office of the United States Navy bought by the rights. Bowditch’s Navigator has been published by the U.S. Government ever since.

Since the first publication, the text has evolved with the advances in navigation practices and continues to serve as a valuable reference for marine navigation in the modern day. The publication describes the principles and factors of navigation, including piloting, electronic navigation, celestial navigation, mathematics, safety, oceanography and meterology. It also contains various tables used in typical navigational calculations and solutions, including the formulas used to derive the tabular data. Today, the “American Practical Navigator” can be downloaded as a single PDF document from the National Geospatial-Intelligence Agency’s website.