Thomas Jefferson and Douwes' method for determining latitude (Q1092884)

Thomas Jefferson was a member of the American Philosophical Society for 47 years and its president for 17 years. As third president of the United States, he sponsored governmental support for science, which he believed could be of benefit to society. Well grounded in both classics and science, he was especially interested in mathematics and astronomy. In 1811 he carried out latitude determinations at Poplar Forest, the estate in Bedford County, Virginia, that he inherited from his father-in-law. The calculations are contained in a manuscript, ``Trigonometry Problems'', which is illustrated and analysed in this note. Jefferson employed a method devised by Cornelius Douwes and simplified by Nevil Maskelyne. A detailed account is given of Jefferson's calculations, followed by a trigonometrical formulation of the method devised by C. H. Cotter in 1968.