Practical navigation: or, An introduction to that whole art [electronic resource] : Containing 1. Several definitions in geometry, astronomy, geography, and navigation. 2. A new and exact kalender, shewing the suns declination and true place, for 60 years. 3. And an almanack of the moon for eight years. 4. The calculation of triangles, both plain and spherical, and their application in navigation. 5. The form of keeping a journal, or sea reckoning. 6. Several useful tables, as tables of meridonal parts; latitudes and longitudes of places, &c. 7. The original invention of the mariners compass. 8. A discourse of the variation, and the natural causes thereof. 9. The description and use of the most necessary instruments in navigation, as the cross-staff, quadrant, azimuth compass, &c. the inclinatory needle, to find the latitude of a place without observation of sun or stars. 10. With an appendix, shewing the secret virtues of the load-stone. By John Seller, compass-maker