The elements of navigation; containing the theory and practice. With the necessary tables, and compendiums for finding the latitude and longitude at sea. To which is added, a treatise of marine fortification. Composed for the use of the Royal Mathematical School at Christ's Hospital, the Royal Academy at Portsmouth, and the gentlemen of the Navy ..
John Robertson's navigation textbook, issued in London by C. Nourse in 1786 with additions by William Wales, taught spherical trigonometry, nautical astronomy and marine fortification to cadets at Christ's Hospital, the Royal Academy at Portsmouth and naval officers. The plates are engraved geometric diagrams numbered by problem: circles crossed by solid and dashed arcs, lettered points, and italic captions useful as line motifs and chart ornament.
