A new and general introduction to practical astronomy [electronic resource] : with its application to geography, in describing the Earth. Topography and hydrography, in describing Places on Land and at Sea. Horometry, or the Measurement of Time. The Trial of Time-Keepers. The Obliquity of the Ecliptic. The Magnetic Variation, and Variation Charts of the Ocean. Refraction and Parallax. The Horizons of the Spheroidal Earth. Surveying the Coasts, and correcting the Charts. Observations of Lunar Eclipses, and Jupiter's Satellites. The Construction of temporary, and other Instruments; with tables of the sun and fixed stars, and a variety of interesting copper plates. The whole being designed, As a Course of plain and easy Instructions and Operations, preparatory to the discovery of the longitude. By Samuel Dunn, Teacher of the Mathematical and Philosophical Sciences, London.